VIA Teams Up Pentium 4 With DDR-Memory — THG.RU

Bringing Pentium 4 To The Masses

Intel’s Pentium 4 has now been shipping for roughly nine months, but it was never able to become a real mass product. Intel’s initiative to offer its flagship processor at rather competitive prices might have improved the situation a little bit, but the real problem still remains Pentium 4’s expensive platform. Until now, the only chipset that supports Pentium 4 is Intel’s 850, which requires the unreasonably expensive RDRAM memory.

Intel has made it very clear that it wants to sell a lot of Pentium 4 processors in all segments, especially once the new spin with the improved 0.13-micron ‘Northwood’-core for the new Socket478 is ready. What it takes is a chipset alternative that supports inexpensive memory. That’s why Intel will soon release its i845 chipset, which is able to operate with the very inexpensive, but also rather slow PC133 memory. The i845 chipset is technically also able to operate with the much faster DDR-SDRAM, but customers will have to wait for this version until 2002, as validation issues or other strange dealings are keeping Intel from an early release.

VIA Filling The Gap

This is of course the big chance for the Taiwanese chipset (as well as CPU and GRX) maker VIA, because it could fill this performance gap between i850/RDRAM and i845/SDRAM with its Pentium 4 chipset P4X266, which happens to support DDR-SDRAM. It could make Pentium 4 more attractive than ever before, since it would combine Intel’s highly clocked Pentium 4 processor with the well performing DDR-SDRAM memory and an attractively priced VIA chipset. Intel would not participate on the chipset sales, but should still appreciate a sales boost of its Pentium 4 processor.

We have already seen a very early version of the P4X266 a few months ago at Computex 2001, where it was supposedly outperforming an i850-platform in 3DMark2001 at 1600x1200x32. In the meantime VIA was able to put together a reliably working motherboard sample as well as a release strategy with NDA and testing procedures, to go life with P4X266 on August 14, 2001 — the same day as the ATi Radeon 8500 release. I managed to delay this article because of several logistic as well as personal reasons (VIA’s marketing department played a rather sad role in it too), but I hope you will still be able to enjoy it.

Here you see VIA’s reference board VT5580A with P4X266 chipset and Socket423 for current Pentium 4 processors.

Pentium 4 Chipsets

So far only one platform has been available for Pentium 4, Intel’s 850 RDRAM chipset. Now VIA is starting to ship its P4X266 and in a few weeks Intel will release the first ‘step’ of the i845 chipset. We made a little comparison table to give you an overlook of the different features.

* depending on clock generator chip

We know that i850 is an RDRAM-only solution, which makes it expensive. Its dual-channel Rambus architecture however allows a memory bandwidth of up to 3200 MB/s, which is identical to Pentium 4’s processor bus bandwidth.

Pentium 4 Chipsets, Continued

Intel’s upcoming ‘low-cost’ solution for Pentium 4, the i845-chipset, will initially only support PC133 SDRAM, which cuts its available memory bandwidth down to a mere 1033 MB/s. We have shown in a previous article that this low memory performance slows down Pentium 4 quite badly. By the end of this year or at the beginning of 2002 Intel will also allow i845 with DDR-SDRAM. This will double its memory bandwidth and should finally enable a reasonable performance of i845 platforms. The official reason for this delay are validation issues, as Intel seems rather displeased with the current chaos in the DDR-memory market, which is missing tight specifications that would ensure reliable operation of each DDR-SDRAM module (Intel: «Neither AMD nor VIA tried to do anything about it»). There’s also still the old Rambus conspiracy theory, which claims that Intel is unable to supply i845 with DDR-support because of license agreements with our friend Rambus Inc.

VIA’s P4X266 supports any kind of SDRAM or DDR-SDRAM. Once teamed up with PC2100 DDR-SDRAM, the available memory bandwidth is with 2133 MB/s still lower than what Intel’s 850/dual-channel RDRAM solution is able to offer. It is rather questionable though, if the mere memory bandwidth number is indeed able to tell the whole story. Most applications require low latency as well, and that is where RDRAM hasn’t been able to outdo SDRAM or DDR-SDRAM solutions so far.

Here’s a table that shows the memory bandwidth numbers of the different memory types.

The table shows quite nicely, that of all single-channel memories, PC2100 DDR-SDRAM is the one with the highest bandwidth. However, we should not forget that one SDRAM or DDR-SDRAM channel requires 64 data lines, while RDRAM only requires 16. That is why a dual-channel Rambus solution requires 32 lines only, which is easier to implement, as long as there aren’t any problems to deal with the very high memory clock of 400 MHz. The dual-channel DDR-SDRAM solutions listed at the bottom of the chart are currently only realistic with NVIDIA’s nForce chipset. The nForce chipset as well the nForce reference boards show that dual-channel DDR-SDRAM is indeed doable. A dual-channel PC2100 DDR-SDRAM solution beats the bandwidth numbers of all other memory configurations.

VIA’s P4X266 Chipset

The picture with the schematics of P4X266 doesn’t reveal anything particularly exciting. The new north bridge VT8753 communicates with Pentium 4, the memory, AGP and the south bridge (via V-Link). The south bridge is already known from e.g. the KT266 chipset. It comes with the usual bells and whistles.

Software Optimized For Pentium 4

Right now there’s not a whole lot of applications that would make proper use of P4’s SSE2-instructions. Windows 2000 can be accelerated using Intel’s Application Accelerator (IAA), which mainly improves I/O performance. Windows XP however carries several P4-optimizations. The latest 3D-games are also starting to come with SSE2-enhancements, like e.g. Dronez and Black&White. We can show you two screen shots of the latter to see the difference between the normal and the P4-optimized version.

You can see that the lower of the two screen shots shows the Black&White world in more detail.

Testing Procedure

We compared VIA’s P4X266 reference platform to our i850 reference board Asus P4T with PC800 RDRAM. The DDR-memory used in the P4X266-board was PC2100 DDR-SDRAM with a CAS latency of 2, which is still difficult to get. It is obvious that the performance of VIA reference board would be lower if we had used the commonly available CL 2.5 DDR-SDRAM DIMMs.

This test was conducted in our European lab, which turned out to be a clear disadvantage, as we were not given by far as much time to test this platform as our US colleagues. A VIA-representative delivered the board to us and stayed with us for a few hours only, in which we had to conclude the whole testing procedure. After our time was up the VIA-group took the board and left us. I strongly protest against this procedure. On that day, the sample board was tested by two other publications in Munich as well, which gives you a good idea how little time we actually had.

Benchmark Setup

Quake 3 Arena 640×480

The screen resolution of 640×480 may not be used by anyone anymore, but it is still the best way to compare processor or platform performance, because it eliminates the graphics as the performance bottleneck. Intel’s i850 chipset is clearly scoring better than VIA’s P4X266.

The story isn’t any different under Windows 2000. i850 beats P4X266 with a margin of about 5 — 8%.

Quake 3 Arena 1024×768

At higher resolutions the limiting factor is the graphics card, which is why P4X266 is able to catch up with i850.

Windows 2000 does change the picture one bit. The differences between the two P4-platforms are rather small.

AquaNox AquaMark

Under Windows 98 the differences are once again very small between the two contestants.

In Windows 2000 i850 is once more able to score a bigger lead over P4X266, but both are scoring lower results than under Windows98.

Unreal Tournament

The difference is rather small, which shows once more that Unreal Tournament doesn’t agree that well with Pentium 4 or RDRAM.

Under Windows 2000, Intel’s 850 chipset and its RDRAM can leave P4X266 a bit further behind, but we are still only in a 5 -7 % range.

3D Mark2001

It is interesting to see how different this benchmarks behaves under Windows 98 and Windows 2000.

While under Windows 98 the scores of both platforms are high and pretty close to each other,

the differences between the two contestants get rather huge under Windows 2000, but both contestants score pretty sad overall numbers. I guess that the latter score is close to negligible, because the majority of gamers are probably still using Windows 98 or Windows ME.

MPEG4 Encoding With FlasK MPEG And DivX

One of the strengths of Pentium 4 plus i850 and RDRAM is certainly the MPEG4-encoding process. In this benchmark P4X266 is almost 10% behind i850.

SiSoft Sandra STREAM

It is not surprising that i850/RDRAM is able to beat P4X266 in this test, bearing in mind that i850 and its dual-channel RDRAM architecture offers a peak bandwidth of 3,200 MB/s, while P4X266 with PC2100 DDR-SDRAM is only able to go up to 2,166 MB/s. However, it is interesting to see that P4X266 comes closer to its theoretical maximum than i850.

Conclusion — Pentium 4 Without Rambus Is Very Attractive

The reason for the poor success of Pentium 4 so far has to be found in i850 and its Rambus-only architecture. A RDRAM RIMM costs still more than twice than a DDR-SDRAM DIMM of the same size. Intel’s upcoming i845 chipset might be able to change this picture, but its initial lack of DDR-SDRAM support will ensure that a large amount of performance conscious people won’t be interested in Intel’s low-cost solution. After all, you can get an AMD processor platform with better performance for less money.

VIA doesn’t share Intel’s concerns or any unfortunate deals with Rambus. The P4X266 chipset is being released with SDRAM as well as DDR-SDRAM support right from the start. While P4X266 might not be able to beat i850 in any of our benchmarks, it is still close enough to make it a very attractive product. Even performance freaks will have a difficult time to notice a difference between the two in actual applications. VIA’s P4X266 is not just the ‘best bang for the buck’ in terms of P4-systems right now, it is a serious enough competitor of i850.

My old friend Richard Brown from Formosa Plastic (or is it indeed just VIA, Richard?) told me this week that P4X266 has so far turned out to be close to perfect from the technical side of things. The reference boards are running reliably and it is not very difficult to design a motherboard with P4X266, as the differences to other DDR-chipsets from VIA are rather small. In fact, the board designs of the large OEMs and motherboard makers (actually the same) have all been finalized already, so that things are ready to go. There is only one little problem. Intel is willing to keep VIA from shipping P4X266 and it might have legal handle. VIA and it’s CEO Wenchi Chen aren’t impressed though. Wenchi even offered motherboard makers that VIA would pay their legal fees in case that Intel should sue them.

You see that it’s all down to politics. P4X266 is certainly a viable product that could introduce Pentium 4 to the mass market. Unfortunately that ain’t good enough for Intel. The guys in Santa Clara want to have it all, the processor as well as the chipset sales. Maybe it’s still smarter to buy AMD processors and stay out of the whole mess.

VIA has recently been getting quite gutsy. That’s certainly something that earns my respect. What only earns my serious anger though is that the marketing department wasn’t able to ensure a fair testing procedure worldwide. Publications that are significantly smaller than us were given more than triple the time to test P4X266 than we were. It goes without saying that I don’t appreciate writing articles based on crippled benchmark data.