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KVM Switches - <BR>Running The THG Obstacle Course
Краткое содержание статьи: Keyboard/Video/Monitor Switches aren't for the rich and famous any longer! We look at 5 KVM switches that can handle many needs at a reasonable cost.

KVM Switches - <BR>Running The THG Obstacle Course

Редакция THG,  17 октября 2001


The idea of being able to switch between multiple computer systems on the fly is not a new one. In the server world, most IT shops have used technology like this to control multiple servers in rack configurations for many years. The benefit of this is that it only requires one keyboard, one pointing device, and, of course, one monitor. Besides the obvious benefits of reducing costs and taking less physical space, switching also reduces costs not normally considered, such as reduced energy usage.

The days of this switching technology, or what is called KVM (Keyboard/Video/Mouse) technology, being exclusive to IT shops is over. Many home PC users are now looking for a way to use both their new and old systems without having to purchase an additional monitor, keyboard, and mouse.

The two biggest traditional complaints about switching technology have been that it doesn't work very well and that it costs too much. However, when compared with the cost of adding a second monitor, keyboard and mouse, today's KVM switches overrule these issues.

Many of the fancy bells and whistles that IT folks have come to expect with high-end KVM switches are now making their way into the commercial arena. These new KVM switches even include a few new features that are targeted at the home user or power user. Best of all, the prices have come way down. Previously, it was not uncommon to spend about $350+ for a fully equipped KVM switch, but now it can cost about half of that amount.

The technology that goes into making a good KVM switch isn't that advanced. The factor of keyboard powered units vs. external powered units didn't really make that much of a difference in our testing. Resolution limitations of some KVM units might pose a problem if you don't get a KVM unit that supports the resolutions that you require. However, many companies claim that their units will handle resolutions far beyond the specs claimed on the box.

In our testing, we found that it was more important to use good quality cables and follow the instructions in the manual to the letter. I could go into a long winded explanation of how KVM switches work, but, to be honest, I found this to be boring, and I am sure that most of you would, too, so I will spare you the explanation.

New Features

New features that are just now starting to be found in KVM units are USB and audio switching. Support for USB can take a couple of different forms. One technology of USB KVM switching allows the user to support USB Keyboard and USB pointing devices. The other technology allows the user to not only support the switching of USB keyboards and USB pointing devices, but also allows the sharing of other USB devices that might be plugged into the USB port. You then have the ability to share your USB scanners, USB cameras, USB storage devices and USB gaming devices between both of your systems. USB support for Apple MAC USB compatible systems was found in several units. We did not test the KVM's ability to be used in an Apple MAC USB setup.

Also, the ability to use one set of speakers and share them between two computers that are being switched is one of the best ideas that I have seen come along in some time. Although this isn't widely supported as of yet, we expect to see more companies adopting this technology in the near future.

Cable management and cable connection is another area that we examine. Some KVM units do this better than others; many have cables running every which direction, which isn't well organized or managed. When using a KVM in a two-port setup, you could have as many as twelve cables that need routing, so efficient cable management can be an important issue. Only one of the companies that we looked at offered any innovative developments in the cable management department.

When looking at the cost of the KVM units in this review, you need to give attention to the information reguarding the included (or lack thereof) cables. Having to purchase additional cables can raise the cost of your KVM unit significantly if all of the required cables are not included. Units that include all of the essential cables will cost a little more. If you have to purchase additional cables, it can raise the cost of the KVM from $30 to $100, depending on which additional cables you must purchase.

In this article we will look at five products that allow you to "hit the switch" and change between systems at the touch of a button. Our focus in this review is on two-port units that provide switching for two systems. (However, we did look at one four-port unit, to provide you with a better idea of the difference between a small office or desktop KVM vs. the bigger guns of a business oriented KVM.) This number of ports are normally more than enough ports for use at a desk at work or in a home environment. (Important note: we do not attempt to address the use of KVMs in the rackmount/server arena in this review!)

OmniView SOHO 2-Port KVM Switch With Audio PS/2 and USB Platform - F1DS102T - Belkin Components

OmniView Soho 2-Port KVM

Besides having one of the longest names for any product that I have ever seen, Belkin enjoys the position of being a leader in the KVM market. Belkin has been building KVM units in one form or another since 1995. All of this experience does not go to waste, as Belkin has developed some of the best-known KVM units in their OmniView product line. Belkin claims that they have over one million OminView KVMs in use today.

The OmniView SOHO 2-Port KVM Switch with Audio PS/2 and USB Platform or the F1DS102T, as I prefer to call it, is a radical departure from more traditional KVM units. This unit accurately aims at the SOHO or the computer professional who have the need for a KVM.

F1DS102T Specifications
Number Of Computer Controlled 2
PS/2 Keyboard & Mouse Support Yes
USB Support Yes
Max Video Resolution Supported 2048x1536@85Hz
Keyboard Switching Supported Yes
Auto Scan Support Yes
Firmware Upgradeable Yes
Cables Included No
Warranty 5 Year Limited Warranty
Cost $149 MSRP

The first thing that you will notice when looking at the F1DS102T is the unit's odd shape. It is oval shaped, stands up vertically, and fits into a "Star Trek" shaped base -- very high tech looking, unlike any other KVM unit in this review. When Belkin designed the F1DS102T, they chose a unique design that, in my opinion, better addresses the needs of the user than any other KVM units before it.

The main reason for the new shape is an advanced cable management strategy which directs all of the cables out of the back of the unit using a removable cable shroud. The cable shroud snaps in place on the back of the unit in such a way that the cables stay organized, out of the way, and hidden from view. I found this to be a more unique cable solution than any of the other KVM units that we tested, and personally really helpful.

OmniView SOHO 2-Port KVM Switch With Audio PS/2 and USB Platform - F1DS102T - Belkin Components, Continued

Back View OmniView Soho 2-Port KVM

While I am on the subject of cables, it is important to note that the F1DS102T does not include any cables other than the special serial cable that is required to flash the unit. Belkin offers a complete line of cables that are compatible with the F1DS102T in various lengths that are just right to fit your application, but they must be purchased separately.

The F1DS102T can be powered from the PS/2 port or the USB port on your computer. It is able to accept a separate power supply, if need be, but we found that wasn't necessary in our testing. The powered keyboard emulation technology worked well and we didn't encounter any "keyboard or mouse not found" messages during the switch and reboot of systems. The F1D065-PWR 9V DC 600mA Power Adapter is availible from Belkin for an additional $17 US.

An advanced feature of the F1DS102T is the ability to upgrade/flash the on- board firmware of the unit. This is a first in the KVM market. KVMs have often been plagued by compatibility issues in one form or another. Belkin looks to rid users of this problem by giving the user the ability to update the unit's firmware. Using the enclosed custom serial cable, the user is able to download firmware updates for the F1DS102T from Belkin's web site. Gone are the days when the scroll button on the mouse does not work, which was an issue in many earlier KVM products. Only Belkin offers the ability to flash upgrade the firmware of their KVM.

OmniView SOHO 2-Port KVM Switch With Audio PS/2 and USB Platform - F1DS102T - Belkin Components, Continued

The introduction of the F1DS102T also proved to be the first KVM unit that offered audio switching support. Yes, that is right! Now, for the first time, not only can you share the monitor/keyboard/mouse, but you can also share one set of speakers between two systems. This is the feature that I really liked best about the F1DS102T, and it is a feature that I think is long overdue in all KVM units. The F1DS102T offers both stereo speaker 3.5mm mini jack and mic support. It would have been nice to see the F1DS102T offer support for both front and rear speakers, but we will have to wait till the next version of the F1DS102T to see that, because it isn't included with the F1DS102T. This is important if you have a sound card that has both a front and rear output.

Another interesting feature is the auto scan feature which allows you to stay on one port before switching to the next port every ten seconds. The time interval can not be changed. The AutoScan mode is good in a situation where you are not necessarily using the systems, but would like the flexibility to monitor the activity of the system every ten seconds, such as in a server environment. When the AutoScan mode is enabled, it can be aborted by pressing the space bar.

Selecting computers on the F1DS102T is a very simple task. You can use the buttons on the front of the F1DS102T, or you can keyboard hot key commands. Both of the command sequences for the F1DS102T start with SCROLL LOCK - SCROLL LOCK and then the command, which can be either an up or down arrow key or a number. I found the buttons on the front of the F1DS102T on the small and narrow side, but the lighted indicator is a very nice touch. It is easy to glance at the unit and know which KVM port/computer you are currently using with the indicator lighting.

Belkin includes both a Users Manual and Quick Installation Guide with the F1DS102T. The manuals are extensive and use ample illustrations on how to connect the unit. I found the manual to be very well written. The FAQ and trouble shooting sections of the manual are concise, and should address almost any issue that a user might have with the F1DS102T.

The performance of the F1DS102T in our testing was good, and we didn't really find any problems. The F1DS102T produced an excellent picture and had no trouble switching between systems. An issue that I do have with the F1DS102T is that there are no included cables, as I mentioned above. Belkin suggests the reason for this is to provide the user with more options and flexibility in the setup and configuration of the F1DS102T by letting the user purchase the cable lengths that best suit them.

I found this to be a difficult sell: if you add just two of the Gold Series PS/2 6-foot cable kits and the required audio kits, this will add almost $125 US to the total cost of the F1DS102T, bringing the total cost of the F1DS102T to about $275 US. Quality and features do cost money, but $275 is steep for home and non-professional users wanting a low cost KVM solution. However, if you want a KVM with one of the most complete feature sets available, this is the one, although it is a bit pricey.

Overall, I found the F1DS102T to be an excellent product with a very unique and functional design. Belkin has done a good job of adding new, very useful features to the KVM arena with this product. Other companies are going to have to add these new features in order to stay competitive with Belkin. Belkin also offer a four-port version of the F1DS102T called the F1DS104T.

KVM100SK - KVM 2-Port Switch Kit - Linksys

KVM 2-Port Switch Kit

Linksys is probably better known to most users for its networking products, such as Linksys NIC cards and CABLE/DSL routers, than for its KVMs. Linksys started selling their line of KVM products some time ago.

While the Linksys KVM products might not be as popular as some other KVM manufacturer's KVMs, they do have the advantage of low cost. The KVM100SK is one of the least expensive KVM units that we tested. Instead of going toward new features, Linksys has stayed its course with known basic functionality.

KVM100SK Specifications
Number Of Computer Controlled 2
PS/2 Keyboard & Mouse Support Yes
USB Support No
Max Video Resolution Supported 1920 x 1440
Keyboard Switching Supported No
Auto Scan Support No
Firmware Upgradeable No
Cables Included Yes - Complete Set Of 4ft Professional Grade Cables
Warranty 1 Year Limited Warranty
Cost $144 MSRP

When looking at the KVM100SK, understand that the KVM100SK is built for the budget-minded user. This does not mean that the KVM100SK doesn't have something to offer, it means that the functionality offered isn't at the level of some of the newer KVM units in our test.

The KVM100SK is a two-port PS/2 only design. The KVM100SK includes no support for USB. The KVM100SK is also compact. It is only 5.0" x 3.9" x 1.3", which makes it the second smallest unit in our review. The KVM100SK does not have anything on the bottom of the unit to make it wall mountable.

One of the main advantages of the KVM100SK is that the price of the unit does include a complete set of professional grade four-foot cables. These cables are molded together to help reduce the cabling mess normally associated with KVM units. The connectors on the cables are colored to match the input connectors on the back of the user's PC for faster installation.

KVM100SK - KVM 2-Port Switch Kit - Linksys, Continued

The KVM100SK itself is pretty easy to operate. It includes one big blue button on the top of the unit that is used to switch between PCs. The top of the unit also provides a lighted indicator on the top of the unit to show you which PC you are using.

Back View KVM100SK

As you can see from the picture above, the inputs for the unit are on three specific sides of the KVM100SK. The front of the KVM100SK is for PC 2, the rear of the KVM100SK is for PC 1, and the side is for the monitor, PS/2 Keyboard, and PS/2 pointing device/mouse.

As you can imgine with a layout such as this, there are cables running everywhere and every direction. The KVM100SK makes it more difficult to control the cabling than any of the other units we reviewed. You almost always will have to bend at least one or two of the cables, which is a disadvantage. I could better understand the positions of these inputs if Linksys would have offered a bracket to allow the mounting of the unit on a wall, but this isn't an included feature. Sitting on top of a desk, the layout of the cables in the KVM100SK can became a cabling nightmare very quickly.

I found the manual and packaging of the KVM100SK to be average. The included manual included no pictures to help the user get the unit connected. This might not be important to an experienced user, but could pose a big challenge to a novice user.

Overall, the KVM100SK is a very "plain jane" unit with limited functionality. It performed well in our testing and we didn't encounter any problems during our use. If you are looking for a unit that will not break the bank, and you don't need or want USB support, the KVM100SK is a great value for the money. Also, the included professional grade cables really make this unit a true value. The KVM100SK works, and that is the important thing, but you do not get the bells and whistles of other KVM units at this price point.

GCS102U - MiniView 2 Port USB KVM Switch - IOGEAR

2-Port USB KVM Switch

Iogear offers the GCS102U 2 Port USB KVM Switch, and what is truly different about this unit is that it offers only USB support. The GCS102U is the only unit that we tested that did not offer any PS/2 support.

While offering only USB support in a KVM product is a new idea, let's see how well the GCS102U stacks up against the other KVM units in this review.

GCS102U Specifications
Number Of Computer Controlled 2
PS/2 Keyboard & Mouse Support No
USB Support USB
Max Video Resolution Supported 1920x1440
Keyboard Switching Supported No
Auto Scan Support No
Firmware Upgradeable No
Cables Included Yes - 2 cables included for both the VGA and USB connection.
Warranty 3 Year Limited Warranty
Cost $149 MSRP

The first noticeable feature of the GCS102U is its size: it is small, coming in at about 4.5" x 2" x 1.5". It is the smallest of all of the KVM units that we tested. The GCS102U included two open areas that were molded into the bottom of the GCS102U, which allows this unit to be wall mounted it desired, a nice feature.

The design of the GCS102U is unique in the fact that this unit includes the input for both the USB keyboard and Mouse on the front of the unit. The unit is a powered unit and requires the use of the included 5V power supply.

Back View GCS102U

GCS102U - MiniView 2 Port USB KVM Switch - IOGEAR, Continued

After plugging the keyboard and mouse in the front of the GCS102U unit, the rest of your required cables and the power supply plug into the back of this unit. It includes a lighted indicator which lets you know which PC is selected, and also serves the function of a selector button. The selector button provides a firm click to let you know when it has been pressed.

Unlike some of the other KVM units in this review, the GCS102U is hot swappable, which allows a user to remove the devices while the unit is powered. Although I am not sure why you would need to do this, it is a nice feature to have, nonetheless.

The cables that are included with the run are about four feet long and include both a VGA cable and a USB A to B cable. Installing the unit is pretty straight forward: plug the VGA monitor into the console, VGA DB15, and run the cables from the GCS102U to the computers.

The USB function of the unit works similar to a USB hub. Basically, it allows a user to share the USB keyboard and the USB mouse that are plugged into the front of the unit via the USB A to B cable that runs out of the back of the unit. In order to share additional USB devices, a user must have a hub plugged into the GCS102U. The only devices that can be shared have to be plugged into the GCS102U itself.

The manual that was included with the GCS102U did not even cover the GCS102U unit. The manual was written for the more advanced GCS124U KVM. This manual does cover the basics of KVM technology and how to hook up a KVM unit, but the information provided is very generic. It requires a user to translate this information to the GCS102U, which could lead to some confusion.

In our testing, we found that the GCS102U unit worked well, but in some instances the computer insisted that it was detecting new hardware after a switch was made. This didn't happen every time, but often enough that I thought I would mention it. After using the GCS102U unit for a while, when gaming with the unit I felt that the USB mouse response was on the sluggish side. I was able to raise the sensitivity of the mouse, which seemed to help somewhat. The display quality of the GCS102U was very good. I saw no loss of picture quality with this GCS102U installed.

Overall, like the Linksys KVM100SK, the GCS102U KVM is an excellent value. With the included cables and small size factor, it does not take up a lot of room on your desk and provides good performance for the price. I liked the fact that the unit was so small and that it was a little different from others that we tested. It will make a welcomed addition for users that want a KVM with only USB support.

GCS124U - MiniView USB II - 4 Port USB KVM Switch (Hotkeys/OSD) - IOGEAR

4 Port USB KVM Switch

Although four-port units are not the focus of this review, Iogear asked us to look at the more full featured GCS124U KVM in addition to the GCS102U KVM.

The GCS124U KVM is more akin to a KVM that you would find a computer professional using in an IT shop. The GCS142U includes support for more computers and includes some additional advanced features.

GCS124U Specifications
Number Of Computer Controlled 4
PS/2 Keyboard & Mouse Support Yes
USB Support Yes
Max Video Resolution Supported 1920x1440
Keyboard Switching Supported Yes w/OSD Display
Auto Scan Support Yes
Firmware Upgradeable No
Cables Included Yes - 4 Complete Sets Of Cables
Warranty 1 Year Limited Warranty
Cost $299 MSRP

Like the GCS102U KVM, the the GCS124U KVM only supports USB. The GCS124U offers no PS/2 support. The GCS124U includes a plastic stand that is fastened to the unit, which allows the unit to be stood on its side, as shown in the picture below. The four feet on the bottom of the unit are fastened with screws and can be removed, allowing the unit to be wall mounted. In addition to the wall mounting option of the GCS124U, Iogear's G2X007 kit can be used to transform the GCS124U into a 1U rackrount KVM. The GCS124U KVM can be expanded by daisy chaining additional MiniView II units for additional functionality.

All of the connections to the GCS124U are made from the back. The GCS124U offers no front USB inputs as the GCS102U did. I have to admit, I was growing quite attached to those front USB inputs, and I really did miss them on the GCS124U.

The back of the GCS124U is pretty straight forward. It includes one USB and VGA input for each computer and, of course, the VGA inputs and USB mouse/keyboard inputs for the console.

Back View GCS124U

GCS124U - MiniView USB II - 4 Port USB KVM Switch (Hotkeys/OSD) - IOGEAR, Continued

I was impressed with the construction of the GCS124U unit when compared to others. The GCS124U has a metal casing that surrounds the unit, which makes the unit quite heavy. It was, by far, the most sturdy of the KVM units that we tested. Normally, the weight might cause concern with the unit standing on its end, but Iogear has done a great job with the design of the fastened stand, which does not allow the unit to tip over or move around.

The GCS124U has a big button on the front to enable the auto scan mode. The auto scan mode changes between systems. It can be aborted by pressing the auto scan button on the front of the unit or by pressing the space bar. As far as I can tell, a user is not able to alter the time between switches in the scanning mode.

The GCS124U unit features a lighted indicator which lets you know which system you are currently switched into. The front of the unit has four push buttons for the selection of each of the four systems. I found the size of the buttons to be a little small, but I did like the click-like sound to provide positive indication when the button had been pressed.

The lighted indicators combined with the on screen display (OSD) and keyboard switching of the GCS124U unit work to provide a very well rounded method of access to the unit. The OSD manager is very powerful, and allows the user to control access to each of the systems, as well as switch between them. It is possible to attach additional MiniView II KVMs and control them, all through the OSD manager. The OSD manager lets a user label each port name, which eliminates the problems of being stuck with Port 1, Port 2, etc... This is a very nice feature and can really cut down on the confusion factor. I found the OSD manager easy to get the hang of, and very powerful. It is a welcomed addition to the GCS124U KVM and is a "forgiveness factor" for the small selection buttons on the front of the GCS124U unit.

The GCS124U includes two premium four-foot cables and two preminum six- foot cables. Since this is a four port unit, other companies need to take a lesson from Iogear here and also provide cables of two different lengths. Hats off to Iogear for thinking in advance about the user's needs with this included feature.

The GCS124U features Iogear's patented USB sniffing technology. We found that this was a welcomed addition, and it worked very well in most situations, but when used in a gaming situation, similar to the CGS102U, we found that the mouse response was a little sluggish. I was able to use the mouse control panel to turn up the sensitivity which did seem to improve the responsiveness.

The GCS124U KVM was a great performer and did very well in our testing. The GCS124U is, naturally, more expensive than the other KVM units that we tested, but the four included premium grade cables do help make the cost more justifiable. The GCS124U has additional features not found in another KVM unit in this review. Iogear also does, in fact, offer KVM units with PS/2 ports rather than just the USB. I found the GCS124U construction and performance to be first rate. I believe that Iogear will continue to refine its products, which is going to give Belkin its first real competition in the KVM arena. The GCS124U KVM shows that Iogear is headed in the right direction with its KVM products.

CS-USB21H - KVM 2 Port Switch - Jargy

Front View of the CS-USB21H

From Tom's Hardware in Taiwan, we received the CS-USB21H KVM from Jargy Co. Ltd., a Taiwanese based company. The CS-USB21H, which is also known as the QV-KMMU2HR, is designed and built by Jargy.

The CS-USB21H features a combined interface that allows for both PS/2 and USB connections, but not simultaneously.

CS-USB21H Specifications
Number Of Computer Controlled 2
PS/2 Keyboard & Mouse Support Yes
USB Support Yes
Max Video Resolution Supported 1920 x 1440
Keyboard Switching Supported No
Auto Scan Support No
Firmware Upgradeable No
Cables Included Yes - Complete Set Of Cables
Warranty 1 Year
Cost $??? MSRP

The CS-USB21H is encased in a combination metal and plastic housing. The CS-USB21H has a nice silver finish and is very professional looking unit.

On the CS-USB21H front, there is a large round selector switch which provides for easy switching between systems. The CS-USB21H also has a light in the upper right hand corner indicating which system has been selected. It has a plastic cover over the light with a name card underneath, and the cover can be slid off to remove the name card, allowing the user to write the name of the two systems on this name card. An additional name card is included, as well, with the CS-USB21H KVM.

CS-USB21H - KVM 2 Port Switch - Jargy, Continued

The rear of the CS-USB21H KVM is rather plain. There are console inputs for the VGA, PS/2 keyboard, PS/2 mouse, and USB. The CS-USB21H has input connectors for VGA, PS/2 keyboard, PS/2 mouse, and USB for each of the systems. As you can see by looking at the back of this unit, Jargy has left plenty of room to allow it to manufacture additional units that will handle more systems, something that Jargy currently does. One thing that I did find strange was that Jargy chose not to include two USB ports on the console inputs for both a USB keyboard and USB Mouse.

Back View CS-USB21H

Also, on the upper left rear of the CS-USB21H is a slider switch which allows the user to disable the LED indicator on the front of the unit so that it will not light up. As you can also see from the rear of the CS-USB21H, this unit is a keyboard, or USB powered unit, and does not have an input to accept power.

The CS-USB21H KVM did not include any user's manual with the unit and this is partly due to the fact that Jargy is an OEM (original equipment manufacturer) operating only in the Asian market. Jargy does not sell this unit directly to the public, but contracts with other companies to market this unit under each company's own label. Jargy is working on additional distribution agreements to make the CS-USB21H available in other countries, but right now it is difficult to get it anywhere outside Taiwan or Japan, and the existing documentation is not available in English. It is expected that we will see the CS-USB21H in other countries soon.

Jargy includes two complete sets of four-foot cables with the CS-USB21H, but I would not consider the quality of these cables to be top shelf. The cables are standard, but use a lessor guage of wire than most of the others in our review. This might cause some problems at higher resolutions, but we didn't encounter any problems in our resolution tests. The PS/2 keyboard and mouse cables use a molded deisgn which helps keep the cables together. The USB A-A cable and the VGA cable are molded together as well.

The CS-USB21H unit itself performed very well. It was easy to use and produced a good picture. Based on the information Jargy provided us about this unit, it should be priced in about the same range as the Linksys KVM100SK and Iogear GCS102U, which is reasonable for the features that are included. I found the unit to be quite good and a welcomed addition to the KVM products available, but until we see the finished product with a manual in English and other widely used languages, and distribution is worldwide, I don't know that it will become very popular. I hope that Jargy is able to get this unit into full international distribution, as it does have potential for many users. For the price, it is a good product.

How To Test A KVM

Testing each KVM was more of a challenge than we first expected. Our normal testing methods used to test other products didn't really apply to testing these KVM units. What we came up with is the "Tom's Hardware KVM Obstacle Course." The KVM Obstacle Course is a series of ten "pass/fail" tests that we tried on each KVM unit to see how it was able to function in several real-world tests. Each test was graded using the pass/fail approach.

A "pass" means that the unit functioned correctly and no problems were encountered. A "fail" means that the unit was unable to handle the same test criteria, or the unit didn't perform correctly in that situation. Because of the differences in configuration in each KVM unit, some units could not complete certain tests. Example: The KVM100SK from Linksys does not support USB so, on tests where the unit didn't support the function because the unit does not offer that feature, we indicated that with a N/A ("Not Applicable") on our chart.

Our Testing Configuration For The KVM Obstacle Course

Common Hardware in this test is defined as the monitor, keyboard, and mouse.

Common Hardware
Monitor Mitsubishi 900u Diamondtron NF with a max resolution of 1600x1200 at 75hz NI
Keyboard Microsoft Natural Keyboard Elite w/USB or PS/2 Support
Mouse Microsoft IntelliMouse Explorer w/USB or PS/2 Support
Test System #1
CPU Intel Pentum III Slot 1 933mhz
Motherboard Asus P3C-E - Intel 820 Chipset
Memory 2 - 256MB PC-800 Rambus Kingston ValueRam Part #KVR800X16-8/128
Graphics Card Asus V7700 GeForce 2 GTS 32MB DDR Deluxe
Hard Disks Western Digital WD102BA - 10GB Hard Drive - ATA-66 - 7200 RPM
Western Digital WD205BA - 20.5GB Hard Drive - ATA-66 - 7200 RPM
DVD-ROM Asus 12X DVD-ROM Drive
CD-RW Philips PCRW-804 - 8x4x24x CDRW
Sound Card Turtlebeach Santa Cruz Sound Card
Network 3Com 3CR990-TX-97 NIC
Other Hardware Iomega 250MB USB External ZIP Drive
Case Enlight 7237 MidTower Case - 300 Watt Power Supply
OS Windows XP Professional OEM Release Version
Test System #2
CPU Intel Pentium III Socket 370 900mhz using the Asus 370DL Slockit Card
Motherboard Asus P3B-F Intel BX Chipset
Memory 2-256MB PC-100 RAM ECC - Kingston
Graphics Card Hercules Prophet II MX - GeForce 2 MX
Hard Disks Western Digital AC29100D - 9GB Hard Drive - 7200RPM - ATA-33
Western Digital WD205AA - 20GB Hard Drive - 5400RPM - ATA-33
CD-ROM Asus 50X CD-Rom Drive
CD-RW Mitsumi 4084TE 4x4x8x CDRW
Sound Card Hercules Game Theater XP Sound Card
Network 3Com 3C905C-TX-M
Other Hardware Microsoft Sidewinder Gamepad USB
3Com HomeConnect USB Camera
Xircom/Entrega Hub4u - Powered 4 Port USB Hub
Case Enlight 7237 MidTower Case - 300 Watt Power Supply
OS Windows 98SE w/all Windows Updates Applied

Tom's Hardware KVM Obstacle Course

Test 1 - In Test 1, both computers were plugged into the KVM. Both computers were turned on and booted at the same time. The KVM was left in the "System 1" position. Once both computers were booted and waiting at the login prompt, we pressed the button on the KVM switch and logged into "System 2." While waiting for System 2 to finish running the login script, we switched to System 1 and logged into it as well. Once the login process started on System 1, we switched back to System 2. We then checked to make sure that both the keyboard and mouse worked on System 2. After checking the keyboard and mouse on System 2, we then switched back to System 1 and checked the kyboard and mouse on System 1. In order to pass the test, the keyboard and mouse were not permitted to lock up between the switches of the two Systems, and had to allow login. This test was done in the PS/2 mode. KVM units which supported USB only were excluded from this test, and were noted as "N/A" in the test results.

Test 2 - In Test 2, we looked at different monitor resolutions between the test systems. We set the resolution of Test System 1 to 1280x1024x16 bit, and we left System 2 at the default resolution of 1024x768x32 bit. What was considered a "pass" for this test was the KVM's ability to switch between the two test systems while the screen was properly displayed on the monitor. Of course, the ability of the monitor to handle the change in resolution was tested, but the ability of the KVM to pass the correct signal was what we focused on.

Test 3 - In Test 3, we analyzed the KVM's ability to pass higher resolution signals. Because of the resolution limitation of the Mitsubishi 900u that we used in this KVM test, we only pushed the resolution of each KVM unit to the maximum of the monitor, which is 1600x1200 @ 75 HZ. In this test, we used the Asus V-7700 GeForce2 GTS and set the resolution to 1600x1200 @ 75 HZ. We then switched to System 2 and then back to System 1. If everything was displayed correctly, we considered this a "pass" of this test.

Test 4 - Test 4, which has also become known as "USB Test 1," basically repeats the steps in Test 1, but instead of using a PS/2 keyboard and mouse, we used the Microsoft Natural Keyboard and Microsoft IntelliMouse Explorer in the USB mode. We connected USB port on the KVM to the computer. We then connected the Microsoft USB keyboard and mouse to KVM. We switched back and forth between the two systems and logged in. After getting logged in to the network, we tested both the keyboard and the mouse to make sure that they functioned correctly. If the keyboard and mouse functioned correctly, we considered this a "pass" for this test. KVMs that did not support USB are noted with N/A.

Test 5 - Test 5 pushes the limit of testing what we dubbed "USB Device Sharing", or "USB Test 2." USB Test 2 focused on whether each KVM unit would allow device sharing between systems. We used the 3Com USB HomeConnect Camera and an Iomega USB Zip 250 as the test subjects. We plugged the HomeConnect Camera into System 2 and the Zip 250 into System 1. We loaded the current Iomega drivers on both System 1 and System 2, and loaded the current OfficeConnect Drivers on Systems 1 and 2, as well. After the drivers were loaded on both systems, we prepared both systems for a reboot. After the reboot, we then attempted to access both devices from both systems. If we were able to access and use both devices from either system, we considered the test of this criteria for the KVM a "pass."

Test 6 - In this test, we looked for possbile PS/2 mouse compatibility issues with the extra buttons and the scroll button on the mouse. On System 2, we used the already installed Microsoft IntelliPoint Software and drivers for Windows 98SE Version 4.01. We used Microsoft's built-in test program in the Control Panel feature to see if the scroll button and all of the mouse buttons worked. If the scroll button and all of the buttons on the mouse functioned correctly, we considered this test a "pass." KVM units that have no PS/2 support were indicated by N/A.

Test 7 - In this test, we repeated what we did in Test 6, but instead looked for possbile USB mouse compatibility issues with the extra buttons and scroll button on the mouse. On System 2, we used the already installed Microsoft IntelliPoint Software and drivers for Windows 98SE Version 4.01. We used Microsoft's built-in test program in the Control Panel feature to see if the scroll button and all of the mouse buttons work. If the scroll button and all of the buttons on the mouse function correctly, we consider this test a "pass." KVM units that have no USB support were indicated by N/A.

Tom's Hardware KVM Obstacle Course, Continued

Test 8 - The purpose of Test 8 was to see how the KVM unit responded to power loss. We turned the KVM off, or pulled the power to the KVM. For those units that were powered by the PS/2 or USB port, we pulled the cables out and plugged them back in, once we were sure that the KVM was receving power. Once power was restored to the KVM, we attempted to switch between both systems and used the keyboard/mouse. If we were able to switch between systems and the keyboard/mouse worked, we considered this test a "pass." If the KVM or the system locked up, we considered the KVM to have failed the test.

Test 9 - In this test, while the KVM is switched to System 2, we turned the power off on System 2. We then re-applied the power to System 2 and checked for keyboard/mouse function. What we were looking for here was whether dropping the power while the unit was switched to that system had any effect on switching. We considered a "pass" in this test as having access to both systems when the power was restored and being able to use the keyboard/mouse.

Test 10 - The focus of this test was to test a combination setup on KVMs that support such a setup. In this test, we used the PS/2 port of the KVM to switch the keyboard between systems and the USB port port two on the computers. We use two mice for this setup and plug each of the mice in. The KVM has no pointing device connected to it. We rebooted both systems to see if the KVM functions by switching between the systems. The KVM is considered a "pass" if both the keyboard and the mouse function. KVMs that don't support both PS/2 and USB switching or USB only switching were indicated with N/A.

Obstacle Course Results

F1DS102T - Belkin KVM100SK - Linksys GCS102U - Iogear GCS124U - Iogear CS-USB21H - Jargy
Test 1 - Login w/switch PASS PASS N/A N/A PASS
Test 2 - 2 Resolutions PASS PASS PASS PASS PASS
Test 5 - USB Dev Share N/A N/A PASS PASS FAIL
Test 6 - Mouse Compatibility PASS PASS N/A N/A PASS
Test 7 - Mouse Compatibility USB PASS N/A PASS PASS PASS
Test 9 - Power Loss System PASS PASS PASS PASS PASS
Test 10 - PS/2 / USB Combo Setup PASS PASS N/A N/A PASS


Overall, KVM technology has come a long way. As we concluded in our testing, the KVMs in our testing performed well. I think the five KVM units included in this review represent a good cross-section of the KVM technology that is currently available. For the most part, none of the units had any serious problems with our KVM Obstacle Course, which speaks well of the KVM product arena.

I found the Belkin F1DS102T to be the best of the lot of the KVMs we tested. Overall, it provided more unique features than all of the other KVM units combined. The F1DS102T includes the audio speaker switching and the firmware flash upgrade ability that no other unit provides. As I mentioned above, I really like the cable shroud and found that I was better able to keep the cables organized than with any of the other units. I found the F1DS102T to be the winner of the KVM units tested.

I would like to give an honorable mention to the Iogear GCS124U and the Jargy CS21H KVMs.

Although the focus of this article was two-port units, the four-port GCS124U from Iogear featured some additional features, such as the on screen display and USB port sniffing technology, which are big technology gains. For users who need a four port unit with USB control, the GCS124U KVM is a well manfactured unit with lots of value for the money. Although it appears that the GCS124U is on the expensive side, the included professional quality cables and four included ports make the price a little more palatable.

The CS21H from Jargy was quite a value when compared to the other KVM units in our review. The compact stand-up design helps to keep the cables behind the unit, which aids in cable management. The large dial selector knob is easy to use, and I liked it better than some of the small buttons found on the other KVM units. The LED provided feedback as to which system was selected. As noted in the review, the gauge of wire used in the cables that were included with the CS21H was a little lighter than most of the other KVM units that we reviewed. These cables did perform well in our testing, but at resolutions beyond 1600x1200, higher quality cables with more headroom would likely be needed. Overall, this unit, while more stripped down than some of the other units tested, performed very well for the price and will satisify the needs of most users. However, it is not commercially available under this name due to its OEM status, but this could change if demand for this KVM model configuration continues.

I have used a KVM switcher both at home and in my lab for some years, and find it to be a really useful and time saving feature. Adding a KVM to your PC setup can add value to your current setup and save money, as well as time, when you need to run simultaneous PCs. The KVM products in this review provide some good options. The cost of KVM units is no longer a barrier to owning one, and compatibility and features have improved, so that having a second monitor/keyboard/mouse is no longer required. As popularity and more widespread demand for KVM technology continues to grow, we will continue to provide coverage about new KVM technology as it is released.

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