Bandwidth For The Masses! VIA P4X333 with DDR333 and AGP 8x – THG.RU

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VIA P4X333 with DDR333 and AGP 8x” –>

USB, AGP 8x, DDR333, ATA/133: The Perfect P4 Chipset?

The new chipsets that are introduced from time to time usually lack innovation. Not this time. VIA, formerly “just a chipset maker,” has become the number two in the global chipset market, and now it is putting all its efforts into extending the good reputation that it achieved through a series of successful chipsets. As numerous tests have revealed, the Pentium 4 lacks the bandwidth that’s needed to take advantage of its full potential. Is the P4X333 the platform to remedy this grievance?

It looks like VIA should be able to continue this success story – the new chipset does implement a bunch of features for which most of us have been impatiently waiting. USB 2.0 will be the most important external interface for all kind of computers, and obviously, VIA wouldn’t do without it. The new Southbridge chip VT8235 not only offers USB 2.0, but also includes an IDE interface with support for UltraATA/133. Even though Maxtor is the only manufacturer that ships such drives, there’s certainly nothing wrong in having this most advanced interface. Finally, VIA emphasizes that the bandwidth of their bus between the Northbridge and Southbridge has been doubled, now delivering 533 MB/s (just as fast as SiS, twice as fast as the Intel Hub architecture).

Last but not least, there is a question that this article won’t be able to answer: What about AGP 8x? According to the specs, VIA has implemented the new graphics card interface that finally also doubles the bandwidth between the graphics adapter and the Northbridge. In the past, upgrading from AGP 1x to 2x and 4x always raised graphics performance. A separate article will discuss this topic later. Here, it’s not a primary factor in evaluating the performance of the P4X333 and the new memory interface in particular. Instead, we stick to known factors, such as GeForce 4 TI4600, 512 MB DDR333 SDRAM (CL2.0) and a fast hard drive from Maxtor. Let’s see what this chipset is all about.

VIA vs. Intel: A Quick Summary

A first look at the Northbridge, cooled by a small heat sink.

VIA is dipping its toes into a market that has always been dominated by the chip giant Intel. Intel’s advantage is that it supplies chipsets for their own processors, thus offering a plattform that is both fast and reliable.

The only setback that Intel ever had to suffer was the disaster with the Pentium III chipset ‘i820’ and the so-called ‘Memory Translator Hub’ (or MTH), which was supposed to enable the use of conventional SDRAM memory on a chipset that was designed for Rambus DRAM. Unfortunately, this MTH chip had some bugs that could not been eliminated, and this whole affair was dubbed ‘Caminogate’ – an allusion to the code-name that was used for i820.

As a result of this disaster, Intel phased out the 820 chipset and released the 815 in order to replace the aged BX. A modified version of this chipset (815T) is used today for Celeron and Pentium III CPUs, but through Intel’s mistake, VIA finally gained a strong hold in the market by providing the Apollo Pro 133A chipset which, due to the failure of i820 + MTH, managed to become the fastest PIII chipset at the time.

Since then, products from the Taiwanese company are steadily improving in terms of consistency and performance. Today, VIA is strong enough to push their own technological developments (such as the C3, Eden and now, the first chipset with AGP 8x).

Other Competitors: SiS

However, there is also another competitor that is not dormant – Silicon Integrated Systems (SiS), who has managed to get rid of its “very-low-cost” image within the last months. The first product to surprise us was the 735 chipset for Athlon; today, SiS delivers various chipsets for all of the common PC architectures. The 645DX is their current flagship for the Pentium 4, also supporting DDR333 and 533 MHz FSB, but it lacks support for ATA/133, USB 2.0 and AGP 8x.

While VIA is still fighting for the Pentium 4 bus license, SiS is officially allowed to sell P4 chipsets. This issue could decide whether the P4X333 will be successful or not. In Europe, for example, it’s not quite as easy to get motherboards based on the P4X266A (except for the VIA brands), so it looks like the big motherboard players are still cautious.

Ready For Graphics: AGP 8x Support

The P4X333 is the first Pentium 4 chipset to support AGP 8x (or AGP 3.0, to be more precise). Though the standard has been defined since late 2000, it is not yet introduced through the industry. The upcoming Intel chipsets i845E and i845G both do not support AGP 8x, neither does the just released 850E version. In addition, there are no AGP 8x graphics cards available now, so this may not even be so tragic.

You may wonder why it could ever be necessary to have such a huge bandwidth between the graphics card and the system. On the one hand, the graphics adapter always has the possibility to swap textures and other graphic data to the main memory. Most BIOSes have an item called “aperture size”; here you can define the maximum memory capacity that can be used by the graphics adapter. Machines running with on-board graphics and unified memory architecture (no dedicated video memory available) obviously will benefit tremendously from the bandwidth doubling. But there is quite a lot of traffic on the AGP bus anyway, so we should expect a performance gain in most benchmarks.

The bandwidth doubling from AGP 4x to AGP 8x was mainly achieved by running the AGP at octuple-pumped 66 MHz (resulting in effective 533 MHz) rather than quad-pumping. Doesn’t that sound familiar? Yes, the Pentium 4 does pretty much the same with its system bus. So far, it has been running at 100 MHz quad-pumped (= 400 MHz), while the latest chipsets (850E, 845E) raised the clock speed to 133 MHz. Thanks to this, the FSB and the AGP keep running pseudo-synchronous.

The following table shows the differences between all AGP standards:

AGP 8x uses the same connector as AGP 4x, the only difference is that some pins have been reassigned in order to support the new signaling. As a result, you will be able to run all AGP 8x and AGP 4x graphics cards (at 0.8 V and 1.5 V) – but not AGP 2x! This means that you won’t be able to use graphics adapters that were made before mid-1999. So once again, you will have to sacrifice backwards compatibility in order to get a faster platform.

Please also see:

The Impact of AGP Speed, dated February 2000.

Exploration into Overclocked AGP Graphics, dated March 2000.

The Answer To Bandwidth Questions: DDR333

PC2700 DDR-DIMM from Corsair Microsystems. Such memory was specifically designed to run clock speeds of 166 MHz.

Even though the ATA/133 interface, USB 2.0 and AGP 8x are very important as well as desirable features, they each have less influence on overall performance than the memory controller plus the memory combined. With the clock speed increased from 133 to 166 MHz (double-pumped), the maximum bandwidth of DDR-SDRAM climbed from 2.1 GB/s to 2.7 GB/s (which is why the standards are also called PC2100 and PC2700).

This is still lower than the bandwidth of dual-channel RDRAM (3.2 GB/s), but conventional SDRAM can live with only a fraction of the latencies of RDRAM, thus resulting in equal or better performance (see reviews of SiS645, SiS645DX, VIA P4X266A).

This is also the main reason why the memory clock of RDRAM was increased from 400 to 533 MHz as well (PC1066 RDRAM). Read our recent review of the 850E chipset and the Pentium 4 at 2533 MHz for details. By the way, the test setup that we used there is the same one that we used to review the new VIA chipset. More details later.

When talking about DDR333 memory, we should not forget that there are two types of RAM available: CL 2.0 and CL 2.5 modules. Only a few days ago we published an article showing the difference between fast (CL2) and slow (CL 2.5) memory setups. Basically, shorter latencies and thus CL2 memory should always be preferred.

Many THG readers have been asking about the performance difference between DDR266 at CL2 and DDR333 at CL2.5. Well, the difference is quite significant, or in other words: DDR333 is always faster than DDR266, no matter which timings you are running. Still, we recommend that you go for the faster DIMMs if possible.

P4X333: Chipset Details

Chipset Architecture: On-board Flexibility

Here it is, the P4X333 Northbridge with attractive features (see diagram above)…

… and its counterpart, the VT8235 Southbridge.

Apart from the technical specs and the performance evaluation, the P4X333 introduces a new Southbridge, the VT8235. In addition to the standard features (AC97 sound, serial and parallel ports, IR port, keyboard and mouse controller, PCI bridge), this chip introduces USB 2.0 and UltraATA/133 to the VIA chipset family. Note that both the P4X333 and the VT8235 are pin-compatible with their predecessors P4X266/A and VT8233A, thus making them easily interchangeable.

As a result, motherboard manufacturers can quickly switch their production to accommodate P4X333 without having to make expensive modifications to the production process or to the motherboard layout.

The VIA P4X333 Reference Board

The reference motherboard is equipped with the maximum hardware features that are directly supported by the chipset. That is six PCI slots, an ACR slot, three DIMM sockets for DDR266 or DDR333 DIMMs, AC97 sound system, 100 MBit network adapter and the UltraATA/133 interface. It’s very likely that this motherboard will be available soon with only a few modifications, if any.

Test Setup

Benchmark Results

We ran a total of 25 benchmarks in order to give you a balanced, overall picture of how the P4X333s perform. Please note that all benchmarks were performed with Intel’s latest Pentium 4, the 2.53 GHz model, running at 133 MHz FSB. Due to time limitations, we were not able to re-test all other chipsets for this review, so we chose one main competitor instead.

We chose to pit the i850E against P4X333 for three reasons: First, neither its predecessor P4X266A nor the Intel 845D can run DDR333 at the same pace. Secondly, none of them is able to run the Pentium 4 at 133 MHz FSB, and thirdly, Intel is going to release the renewed 845 chipset with support for DDR333 and FSB133 next week anyway.

Processor Clock

OpenGL Performance: Quake 3 Arena

DirectX 8 Games: 3D Mark 2000 and 2001

MP3 Audio Encoding: Lame MP3

MP3 Audio Encoding: mp3 Maker Platinum

MPEG-4 Video Encoding: Xmpeg 4.5 and Divx 5.01

MPEG-2 Encoding: Pinnacle Studio 7

SiSoft Sandra 2002 Benchmarks: CPU and Multimedia

CPU and Multimedia Performance: PC Mark 2002

3D Rendering Performance: SPECviewperf

Archiving: WinACE 2.11

3D Rendering: Cinema 4D XL 7

3D Rendering: 3D Studio Max 4.2

Conclusion

VIA has finally done it! If you take some time to analyze the benchmark results more closely, you will notice that the VIA chipset is only slightly behind the fastest RAM/chipset combination available out there. Dual-channel PC1066 RDRAM is pretty powerful and provides an awesome 4.2 GB/s peak bandwidth. In contrast, the 2.7 GB/s of the P4X333 looks pretty weak. Yet, the chipset is still able to keep apace!

Two important features could not be included in this article. The first is the ATA/133 interface, which might enable improved performance. Unfortunately, there is no drive available that can make use of the available interface bandwidth. Although Maxtor is already shipping the corresponding drives, they do not make any difference in performance for now.

It’s pretty much the same with the AGP 8x port – even though the P4X333 claims to be ready for this, it’s impossible to get any graphics card to verify it. So the VIA chipset owes us some more answers as soon as AGP 8x becomes hot.

Finally, we can attest to the fact that the prototype motherboard was trouble-free and stable during testing. It offers excellent performance and sophisticated features, making it one of the best investments you can make at the moment, since the Pentium 4 as it is now should still be available for many months to come (at increased clock speeds, of course). Motherboard manufacturers should be able to ship P4X333-based motherboards in large quantities as well, seeing as they do not have to change their existing motherboard designs from P4X266A.