600 MHz with Socket 7: The AMD K6-2+
Редакция THG,  13 июля 2000

Socket 7 Tuning with AMD K6-2+


Who would have imagined this three years ago: Intel says good-bye to Socket 7 and declares Slot 1 to be the next best thing since sliced bread. The Pentium MMX 233 was Intel's last Socket 7 processor. Nevertheless, Socket 7 survived as a processor basis up to now, and with a little bit of overclocking, currently the fastest CPU even reaches 600 MHz. In view of this comparatively old technology it is a sensational result.

The old Socket 7 platform receives a last performance boost now. The K6-2+ is the processor in AMD's portfolio that is capable of increasing the performance in numerous older PC systems. The highlight of this new CPU: It has an integrated L2 cache, and is available with a clock frequency of 550 MHz.

We thoroughly tested the 500 MHz version, and are positively surprised by the performance it offers. A system that was upgraded with this processor achieves the performance of a modern PC, and it is definitely ready for current applications as well as 3D games.

AMD K6-2+ in Detail

AMD K6-2+
Affordable tuning for all Socket 7 systems: The AMD K6-2+ offers a 128 KB L2 cache, and the maximum clock frequency of the processor is 550 MHz. It is possible to overclock the CPU to 600 MHz without any problems.

Processor AMD K6-2+ AMD K6-2
Process 0,18 µm 0,25 µm
Clock speeds 475 to 550 MHz 300 to 500 MHz
CPU Platform Socket 7 Socket 7
System Speed 95 to 100 MHz 66 to 100 MHz
L1 Cache 64 KB 64 KB
L1 Cache Access CPU Core speed CPU Core speed
L2 Cache Interface 64 Bit 64 Bit
L2 Cache 128 KB on-die On board, max. 2048 KB
L2 Cache Clock CPU Core Clock 66 to 100 MHz
L3 Cache On board, max. 2048 KB no
MMX Support yes yes
3Dnow! Support yes yes
MPS Support no no
POwer Saving PowerNow no
VCore 1,4 to 2,0 Volt 2,2 to 2,8 Volt
V I/O 3,1 to 3,3 Volt 3,1 to 3,5 Volt
Power Consumption max. 20 Watt max. 29 Watt

Two types of AMD processors for the old Socket 7 platform: In general the new K6-2+ differs from the old K6-2. The PowerNow technology requires a special motherboard with the appropriate voltage controller.

AMD K6-2+ in Detail, Continued

Contrary to the recent K6-2 version, the new AMD K6-2+ is manufactured in a 0.18µm process. Consequently the power consumption of the new processor is much lower than that of the predecessor with 0.25µm wide conducting paths, and it also requires less core voltage. The table above lists all the important technical specifications of the K6-2+ in comparison to the old K6-2. A special feature of the new CPU is the variable clock frequency that can be changed in 32 steps during operation. AMD calls this technology PowerNow, and its main purpose is to lower the power consumption. Therefore AMD is targeting this processor almost exclusively at the notebook market. The core frequency can be controlled between 1.4 Volts and 2.0 Volts, depending on the actual clock frequency. At a clock frequency of 200 MHz the core voltage is at 1.4 Volts, and the processor consumes only 3 to 5 Watts. The PowerNow technology, which is supposed to work in the Thunderbird and Duron processors in the near future as well, can increase the battery life of a notebook quite significantly. Hewlett-Packard is the first manufacturer offering a mobile PC that is equipped with the AMD K6-2+ and the PowerNow function. Clearly, AMD is positioning its new power management technology against Intel's SpeedStep technology, which was also developed to lower the power consumption of a processor.

The 500 MHz model of the AMD K6-2 achieves a significant performance increase in older PC systems.

Processor 1K unit price
AMD K6-2+/550 $99
AMD K6-2+/533 $85
AMD K6-2+/500 $75
AMD K6-2+/475 $70

Which PCs or boards are suited for the upgrade?

Voltage Jumper
The correct core voltage is crucial: The AMD K6-2+ is specified for 2.0 Volts. In our test it ran completely stable at 2.1 Volts. Higher voltages should be avoided, however.

In principle the AMD K6-2+ fits in every motherboard with a Socket 7 interface. However, in practice there are a few requirements: The motherboard must support a core voltage of 2.0 Volts or a maximum of 2.1 Volts. Quite often this is not the case with very old boards from 1996 and 1997 that are based on Intel's 430HX, 430VX, or 430TX chipset, because the voltage controller on these boards offers a minimum voltage of 2.2 Volts. One of the exceptions is the legendary Asus P55T2P4 (starting with revision 3.x) that supports the required voltage for the K6-2+. Motherboards with VIA VP3, VIA MVP3, Ali Aladdin V or SiS530/5598 chipset that are up to three years old are less problematic, because in most cases the voltage controller supports at least 2.1 Volts.

Multiplier Jumper
5.5 is the limit: The largest possible multiplier is 5.5 for all Socket 7 boards. However: The AMD K6-2+ interprets the setting "2" as multiplier 6

Another important prerequisite is the clock frequency multiplier. The K6-2+/550 requires a multiplier of 5.5, which is actually offered by most boards. In the case of the Asus P55T2P4 there are no references for setting the jumpers for multipliers larger than 3.5, neither on the board itself nor in the handbook. Trying all the different jumper combinations is often the only way to find out the appropriate settings. Because most of the older boards officially only allow a system clock of 66 MHz, the clock frequency must be operated outside the specification. For example both the Asus P55T2P4 and the Abit IT5H (both boards with Intel 430HX chipset) support a system clock of 75 or 83 MHz. Otherwise the maximum possible core frequency of the K6-2+ is limited to 66 x 6 = 400 MHz. Even though no Socket 7 board supports a multiplier of "6", it may still be achieved by setting the multiplier to "2". The AMD K6-2+ interprets this as the value 6. Users who own a board with VIA MVP3, Ali Aladdin V or SiS530/5598 chipset are on the safe side. These components offer a system clock of 100 MHz, allowing you to use the K6-2+ without having to overclock the system bus.

Overclocking: 600 MHz with Socket 7!

This has never happened before: 600 MHz based on Socket 7. Now an old system upgraded with a K6-2+ can achieve the performance level of current PCs.

Our test sample was an AMD K6-2+/500 that ran on an Aopen AX59 Pro without any problems. Because the board does not offer support for 2.0 Volt, we used the 2.1 Volt setting. The marginally higher voltage did not have an influence on the system stability. During the test we discovered surprising results from overclocking: For the setting 5.5 x 100 = 550 MHz as well as for 6 x 100 = 600 MHz we observed no instabilities! This result is a phenomenal considering that the AMD K6 and AMD K6-2 processors have been totally unsuitable for overclocking in the past. The 0.18 µm process technology that generally allows higher clock frequencies is certainly one reason for this behavior. The multiplier and the supported system clock are the only limiting factors for pushing the clock frequency even higher. Overclocking the K6-2+ processor on a suitable motherboard with VIA MVP3, Ali Aladdin V or SiS530/5598 chipset that supports a system clock frequency above 100 MHz could certainly provide an even higher performance gain.

Test Setup

Platform Information
Processor AMD K6-2+/500
L2-Cache Clock 500 MHz
Front Side Bus 100 MHz
Memory Clock 100 MHz
Memory Wichmann Workx PC133 SDRAM 128 MB CL2
(max. 1,1 GByte/sec transfer rate)
Graphics Card Nvidia GeForce
Common Hardware
Motherboard Aopen AX 59 Pro
Network 3COM 3C905B-TX
Hard Drive Seagate Barracuda ATA ST320430A
VIA 4in1-Driver Version 4.20
GeForce Driver Win98 5.30 (OpenGL- and AGP-Support)
Environment Settings
OS Windows 98 SE, DirectX 7.0a
Quake III Arena Timedemo 1, 640x480x16x85
Expendable Downloadable Demoversion, 640x480x16x85
Unreal Tournament Version 4.05b, Benchmark UTBench
Sysmark 2000 1024x768x16x85

Benchmarks and Discussion

We used the same hardware configuration for all the benchmarks. Even though the test sample of the AMD processor was only specified for 500 MHz, the CPU ran at 550 and 600 MHz without any problems. Below is a list of the results for different clock frequencies, compared to the Celeron 500 and the AMD K6-2/500.

Application Performance

Sysmark 2000 - Windows 98 SE, 1024x768x16

In the application benchmark "Sysmark 2000" the K6-2+ shines with excellent results. At a clock frequency of 500 MHz, it leaves the Celeron with the same frequency standing.

Game Performance

Quake III Arena Demo001 - Windows 98 SE, 640x480x16

In the OpenGL game benchmark Quake 3 Arena the Celeron 500 leads the overclocked 600 MHz AMD K6-2+.

Game Performance, Continued

Expendable Timedemo - Windows 98 SE, 640x480x16

The game benchmark Expendable is an indicator for the Direct3D performance. In this case the K6-2+ overclocked to 600 MHz is slightly in front of the Celeron 500.

Unreal Tournament UTBench - Windows 98 SE, 640x480x16

The overclocked AMD K6-2+ showed a very good performance in the UTBench from Unreal Tournament, and leaves the Celeron 500 behind. The K6-II+ processors with lower clock frequencies end up in last place together with the old K6-2.

Conclusion: Affordable Upgrade for Socket 7

Because of its' affordable price of about US$ 107, the AMD K6-2+ is suited for upgrading many Socket 7 systems. Compared to an old AMD K6-2 or even an Intel Pentium 233 MMX the performance gain is enormous. The benchmark results definitely show that a system based on the AMD K6-2+/500 can match a modern PC system based on Slot 1 and Celeron 500.

But the requirements for using the new processor could create problems with some boards: The motherboard should offer a core voltage of 2.0 Volts, the multiplier must allow the setting 5 or 5.5, and the system clock should operate with at least 83 MHz. Boards with VIA MVP3, Ali Aladdin V or SiS530/5598 chipset that support a system clock of 100 MHz are best suited. They are also the first choice for overclocking because they allow a clock frequency of 600 MHz (6 x 100 MHz) without problems.

One big problem is actually the availability of the processors: According to AMD the company currently sells the K6-2+ only to system integrators that use the processor in notebooks. We were not able to find out from AMD how many CPUs will ultimately be sold to retailers.

Gives the results of our tests, we feel they would be doing consumers an injustice if they didn't make the CPU available on a more widespread basis. Come on AMD, give upgraders a chance!


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