Contemporary Socket A Chipsets: NVIDIA nForce2 Ultra 400, NVIDIA nForce2 400, SiS748 and VIA KT600

by Ilya Gavrichenkov
07/08/2003 | 01:26 PM

The introduction of Athlon XP processors intended to work with 400MHz bus pushed the core logic developers to design new chipset versions supporting the new CPUs. As a result, many new mainboards have already arrived and will keep arriving into the market. Among their features will definitely be the support of Socket A processors working with 400MHz bus (200MHz FSB). This way, the new mainboards tending to be called contemporary should be based on absolutely new chipsets, which we haven’t yet taken a really close look at. Today we will try to make up for the missing bits of information on our site and will test several new generation Socket A chipsets. Among them are NVIDIA nForce2 Ultra 400 and its single-channel nForce2 400 version, and two newcomers from SiS and VIA: SiS748 and VIA KT600.

In fact, we wouldn’t call this new round of competition between the Athlon XP chipset developers a thrilling one. The Socket A platform should theoretically start leaving the market this fall, when the new AMD Athlon 64 processors come out. Besides, there is still only one Athlon XP3200+ model, which requires 400MHz bus support from the mainboards. However, the intrigue remained there. Firstly, the mainboards with the officially supported 200MHz FSB will be very popular among overclockers, who are fond of tweaking Athlon XP processors by raising the bus frequency in order to speed up the whole system. Secondly, VIA KT600 is of great interest to computer users today, because according to the developer, they managed to design a single-channel chipset, which sometimes outperforms dual-channel nForce2 Ultra 400 from their competitor – NVIDIA. And thirdly, we are also very much excited to look at the new solution from SiS, because a low-cost chipset with good options for processor overclocking by adjusting the bus frequency can definitely find its fans.

Moreover, the launching of the new chipsets definitely implies that the older ones will be discontinued. In other words, if you decide to buy a new Socket A mainboard one day, you will very soon have to choose from the products based exactly on the solutions discussed today in this article. AMD is going to keep producing Socket A processors for at least a year from now, that is why it would be incorrect to regard the new chipsets as inappropriate or unpromising.

Well, enough of small talk. Let’s finally get acquainted with the new core logic sets.

Closer Look: NVIDIA nForce2 Ultra 400

The new chipset from NVIDIA can not be called “new” in the full meaning of this word. NVIDIA nForce2 Ultra 400 is in fact none other but a new revision of the regular NVIDIA nForce2. What NVIDIA really introduced in the product to make it new is the improved stability when the chipset works with 200MHz FSB and reduced heat dissipation of the chipset North Bridge. Therefore, NVIDIA nForce2 Ultra 400 boasts absolutely the same features set as the regular NVIDIA nForce2, plus officially supports Athlon XP with 400MHz bus and DDR400 SDRAM.

I would like to point out that NVIDIA nForce2 appeared a very successful and popular product. This statement is proven by the fact that NVIDIA nForce2 based mainboards occupy a stable No. 1 position among all Socket A products available in the today’s market, according to the regular sales reports for the past few months. Besides, NVIDIA also deserves all our praise for the fact that their chipset managed to stay in the market for almost a year already without any changes made to it and to compete with the rivals pretty successfully throughout all this time, while VIA and SiS have already launched a few new products within this period. What I am trying to say is that the lifetime of NVIDIA nForce2 appeared very long, which will definitely please those of you who are lucky to own a mainboard based on this chipset, as they are still very up-to-date.

At the same time, it is not very good that NVIDIA hasn’t yet improved the chipset features in any way; they haven’t even designed any new South Bridge versions. So, from some viewpoints NVIDIA nForce2 Ultra 400 yields to its competitors. No, NVIDIA nForce2 Ultra 400 is still the only dual-channel chipset for Socket A platform. It is the unbeaten leader in terms of peak bandwidth of the memory subsystem. However, the South Bridge of this chipset, even its most advanced MCP-T version, doesn’t support SerialATA hard disk drives, and this is a really necessary feature already. That is why most mainboards based on NVIDIA nForce2 Ultra 400 are usually equipped with an onboard SerialATA controller, which definitely affects their price.

For more details on the features of the NVIDIA nForce2 Ultra 400 chipset, please, see our previous article called Contemporary Socket A Chipsets Comparison: NVIDIA nForce2 vs. VIA KT400.

ABIT NF7 2.0 is one of the best mainboards
on NVIDIA nForce2 Ultra 400.

Closer Look: NVIDIA nForce2 400

Watching vain attempts of VIA and SiS to develop a high-performance single-channel chipset for Socket A platform, NVIDIA decided to go on and not very long ago the company introduced one more solution: NVIDIA nForce2 400. in fact, this is the same NVIDIA nForce2 Ultra 400, but featuring only one memory channel. In other words, NVIDIA decided to move from the high-end chipset segment and get some presence in the mainstream as well by offering a solution for mainboards priced around $70-$100. Besides, this way the company could also find an application for the defective NVIDIA nForce2 Ultra 400 chips, which had only one memory channel working properly: they simply disabled one memory channel in such chips and then they were sold under NVIDIA nForce2 400 name.

Today there are hardly any NVIDIA nForce2 400 based mainboards in the market: the mainboard guys are waiting for the VIA KT600 and SiS768 to come, so that they could choose the most profitable solution out of these three single-channel chipsets. However, I would like to point out on my part that NVIDIA nForce2 400 is really good choice. If we disregard the absence of SerialATA support, which is definitely a big drawback for this product, we have to admit that the memory controller of NVIDIA nForce2 400 is very successful, even though it is a single-channel one. Even when we reviewed the very first nForce version we stressed that the major trump of NVIDIA chipsets is not the dual-channel design, but the DASP unit (Dynamic Adaptive Speculative Pre-Processor). The second version of this DASP unit has been implemented in NVIDIA nForce2 400 (just like in NVIDIA nForce2 Ultra 400).

As you know, this block is theoretically like an additional buffer (or cache, if you like it more), which is built into the chipset North Bridge. This buffer receives data, which should be demanded by the CPU later, according to the logical part of the DASP. This way, the DASP unit can use the memory bus more efficiently and reduce the memory latencies quite tangibly on data addressing in case of successful predictions and appropriate data prefetch. It is exactly this particular data prefetch mechanism of the NVIDIA nForce2 400 memory controller that NVIDIA pins its hopes on in competition with VIA. A little later in this review we will see that DASP proved absolutely up to our expectations in NVIDIA nForce2 400 making this core logic extremely attractive from the price-to-performance ratio point of view.

Soltek SL-NV400-64: one of the first mainboards
on NVIDIA nForce2 400.
Note that there are only two DIMM slots onboard.

Closer Look: SiS748

A new chipset from SiS supporting Athlon XP processors with 400MHz bus, SiS748, is also not a brand new solution in reality. In fact, SiS748 is the same SiS746FX with the official support of 200MHz FSB. As you remember, SIS746FX was a derivative of SiS746, which acquired official DDR400 SDRAM support. That is why SiS748 has no new peculiarities from the technological point of view.

As for the performance of the new SiS chipset, it is positioned as a solution for low-cost systems. However, we remember very well SiS735, which used to be the fastest Socket A chipset for a while. That is why we wouldn’t make any forecasts, as SiS748 can prepare us any sort of surprise.

HyperStreaming technology implemented in the new chipset is something SiS is especially proud of. This name hides the MuTIOL 1G bus with 1GB/sec bandwidth and highly original working algorithm, which connects the chipset North and South Bridges. The peculiarity of this bus is a separate independent stream, which is assigned for each request coming from the North Bridge resources to South Bridge resources (or vice versa). As a result, the latencies grow much lower and the requests can be deeply pipelined. However, we could hardly call HyperStreaming a revolutionary technology. Unfortunately, it will influence the overall system performance just a little.

Although SiS748 is a new chipset, it also doesn’t have SerialATA support, like NVIDIA nForce2 400. SiS engineers were probably a little lazy that is why they provide their solution with a relatively old SiS963 South Bridge (or SiS963L without IEEE1394 support). However, the company also offers a SiS180 companion chip together with the new SiS748, which is a separate PCI SerialATA controller supporting RAID. Anyway, bearing in mind the primary target of SiS748 based mainboards, we really doubt that SiS180 will be that widely spread.

Other than that SiS748 is a pretty common single-channel Socket A solution supporting new processors with 400MHz bus, DDR400 memory and AGP 8x.

SiS748 based reference mainboard.
The PCB didn’t change since the times of SiS746.
Also note that there is no heatsink on the chipset North Bridge:
the chipset hardly gets warm at all.

Closer Look: VIA KT600

The new core logic set from VIA, the KT600, is the today’s most exciting solution. It owes this extreme interest of the public to VIA’s marketing people in the first place. Even before the first samples appeared, VIA’s marketing department managed to convince everyone that single-channel VIA KT600 will be able to compete on equal terms with the dual-channel NVIDIA nForce2 Ultra 400. They even mentioned the new technology that will allow KT600 to significantly improve the memory controller performance: FastStream64. VIA claims that their new memory controller with FastStream64 technology features additional data prefetch buffers. In other words, FastStream64 is a sort of alternative to NVIDIA’s DASP. Well, later today we are going to find out if VIA’s engineers manage to achieve the same performance heights as nForce2.

VIA KT600 differs from the predecessor, VIA KT400A only by the official support of Athlon XP processors with 400MHz bus and enhanced memory controller. KT600 boasts full support of 400MHz bus and DDR400 SDRAM having finally acquired a complete set of PCI and memory frequency dividers. Also KT600 comes with a new VT8237 South Bridge. The remarkable thing about this new chip is the SerialATA protocol support. As a result, VIA KT600 based mainboards will have two SerialATA-150 channels. Besides, VIA has also developed special drivers supporting RAID 0, 1, 0+1, which allow building RAID arrays from Serial and Parallel ATA drives in the popular Windows and Linux operation systems. So, the functionality of the new VIA VT8237 South Bridge makes it a worthy competitor even to the recently released Intel ICH5R.

In general, after the unsuccessful KT400A, which was just a slightly modified VIA KT400, the company seems to have finally released a really attractive product. At least this is what it looks like at first glance. Let’s hope that our expectations will come true.

VIA KT600 based reference mainboard.

ASUS A7V600 – one of the first VIA KT600 based mainboards.
Unfortunately, its performance leaves much to be desired.

Contemporary Socket A Chipsets Specifications

Summing up everything we have just said about the today’s Socket A chipsets supporting 400MHz bus, we would like to offer you a table. Keeping in mind that each chipset can be used with various South Bridge versions, we split the table into two parts: one for North Bridge specs, and the other for South Bridge specs.

We will begin with the North Bridges:

As you can see, all chipset specs look very similar, except the only chipset with a dual-channel memory controller – NVIDIA nForce2 Ultra 400. We discovered much more “paper” differences between the South Bridges, which can go with the above described North ones. Have a look:

The situation with the South Bridges is somewhat more interesting. The most advanced versions of NVIDIA South Bridges can boast very rich networking and sound capabilities, but do not support SerialATA, not to mention RAID. VIA, on the contrary, supports SerialATA and RAID, but has nothing similar to NVIDIA’s APU. Although VIA claims that Vinyl Six-TRAC Audio implemented in the VT8237 South Bridge provides no worse sound quality than NVIDIA’s solution if you use it with VT1616 codec. Also VIA’s South Bridges do not support IEEE1394, which is supported not only by NVIDIA’s chips but also by the South Bridge from SiS. As a result, we have to admit that there is no ideal South Bridge today. Each manufacturer’s solution has its bottlenecks, which will be eliminated by the mainboard makers: they will have to add extra onboard controller chips.

Testbed and Methods

The major goal of this test session was to compare the performance of the contemporary Socket A chipsets. We decided to test our solutions not only with the CPUs supporting 400MHz bus, but also with the processors supporting 333MHz bus. Even though the major feature of our today’s testing participants is the support of processors with 400MHz bus, we can’t do without a performance check with the 333MHz bus CPUs.

For NVIDIA nForce2 Ultra 400 we selected ABIT NF7 2.0 mainboard. This solution demonstrates almost the fastest performance today among all mainboards based on the same NVIDIA core logic. For this reason and also because the mainboards based on the single-channel nForce2 400 are not that widely spread yet, we used the same mainboard in single-channel mode to test the single-channel NVIDIA chipset.

As far as the test platform for VIA KT600 is concerned, we used the reference mainboard from VIA. The thing is that the first revisions of the mass products, which we managed to get hold of, didn’t run as fast as the reference mainboard from VIA. That is why we are unable to evaluate the chipset performance appropriately, until the mainboard guys finalize their products completely.

The same is true for SiS748, with that only difference that there are hardly any mainboards in the mass market based on this solution at all. That is why we used the reference mainboard for SiS748 tests, too.

We also used AMD Athlon XP 3200+ processor (400MHz bus, 2200MHz actual core frequency) and Athlon XP 3000+ (333MHz bus, 2167MHz actual core frequency).

So, we had the following testbeds ready:

All tests were run in MS Windows XP Professional SP1. The memory timings were set to maximum performance (2-2-2-5). At 333MHz bus frequency the memory worked at 333MHz and 400MHz; at 400MHz bus – we only used 400MHz memory.

Performance at 333MHz Bus Frequency

Athlon XP processors with 333MHz bus frequency are the most widely spread processors today, and their counterparts with 400MHz bus are very unlikely to spread all over the place in the near future. That is why we would like to check the performance of Socket A platforms with processors supporting 333MHz bus in the first place. As we have already mentioned in this part of our test session we used Athlon XP 3000+ on Barton core working at the actual frequency of 2167MHz.

As is known, the memory controller makes the major contribution to the overall system performance. Therefore, we decided to start with the memory subsystems performance of our today’s testing participants. The table below contains the results obtained with Cachemem utility:

	nForce2 400 DDR333	nForce2 400 DDR400	nForce2 Ultra 400 DDR333	nForce2 Ultra 400 DDR400	SiS748 DDR333	SiS748 DDR400	VIA KT600 DDR333	VIA KT600 DDR400
Memory read speed, MB/s	1661.3	1529.6	1672.3	1541.9	1395.6	1411.8	1545	1554.2
Memory write speed, MB/s	990.8	992.6	1003.9	1001.3	858.8	919.3	644	824.3
Memory copy speed, MB/s	1096.8	1148	1233.3	1233.6	945.2	1040.9	939	1057
Latency	208	260	209	260	233	260	249	243

Well, the results give some food for thought. We would like to draw your attention to a few most interesting things. First, note that the new SiS748 and VIA KT600 chipsets work with DDR400 SDRAM faster than with DDR333 SDRAM. Before, it didn’t make much sense to use Socket A chipsets in asynchronous mode when the bus frequency equaled 333Mhz. Now the situation has changed. The use of DDR400 instead of DDR333 boosts the performance quite noticeably. Although this is not valid for nForce2 chipset family, as they are much faster in synchronous mode, anyway.

Second, we would like to stress that the use of dual-channel memory access in nForce2 Ultra 400 doesn’t have a very big influence on the performance. In fact, we didn’t expect anything different: it is the processor bus and not the memory bus that limits the data transfer rate between the CPU and the memory of contemporary Socket A systems. We also didn’t notice any latencies lowering, which the dual-channel configurations should provide due to alternating requests of the two memory controllers. However, we shouldn’t forget that Cachemem is a synthetic benchmark, and the situation in real applications may be somewhat different.

As for the actual comparison of the results, we would like to say that both nForce2 chipsets are far ahead. It is especially noticeable if you look at the latency: nForce2 (with DDR333 SDRAM) is beyond any competition here. Well, the obtained results indicate very clearly that nForce2 9even a single-channel one) doesn’t have any causes for concern: no dangerous competitors in the market yet.

Now let’s have a look at the results obtained in another memory bandwidth test – SiSoft Sandra 2003 using Stream algorithm.

An absolute leader here is the same nForce2 Ultra 400 with DDR333 SDRAM. The results of this chipset with DDR400 are considerably lower: in this case it even falls behind VIA KT600 and SiS748. As for the single-channel chipsets, NVIDIA nForce2 400 manages to defeat the competitors. Everything indicates that DASP technology implemented in this chipset is an extremely effective way to speed up the memory subsystem. FastStream64 technology from VIA can’t prove any comparable performance improvement, as we see.

The results of the synthetic PCMark2002 also prove our preliminary conclusions. However, let’s now pass over to the platforms performance in real applications.

The popular 3D test, 3DMark2001 SE, reveals the victory of NVIDIA solutions over the rivals. The leader outperforms quite tangibly VIA KT600 and even more - SiS748. Again, we would like to say that the performance of the dual-channel and single-channel NVIDIA solutions doesn’t differ that greatly.

In the newer 3DMark2003 nForce2 proves even more powerful. The gap between the NVIDIA solutions and those by VIA and SiS grows bigger. By the way, note that in this case VIA KT600 and SiS748 run almost equally fast.

The tests in Quake3 Arena once again prove our point. SiS748 and VIA KT600 can’t catch up with the nForce2 solutions.

The results obtained in other benchmarks look the same.

As we can see, SiS748 and VIA KT600 are almost equally fast. Although VIA KT600 is a more frequent winner than SiS’ solution, the performance difference between them is really tiny.

The results show that VIA and SiS optimized their chipsets for asynchronous work with 333MHz bus. That is why the use of DDR400 SDRAM with them allows achieving higher results in most cases. It is especially true for KT600. As for SiS748, it sometimes works faster with DDR333 SDRAM than with DDR400 SDRAM. With NVIDIA nForce2 Ultra 400 and nForce2 400 you’d better give up the asynchronous mode: the chipsets perform much faster if the FSB and memory frequencies are the same.

When we tested the data compression speed, NVIDIA chipsets working synchronously again outpaced VIA KT600 and SiS&48 quite tangibly. Could you imagine that by choosing the proper chipset you could win about 10% of extra performance in a real application!

The similar situation is also observed when we encode video into MPEG-4 format. By the way, we would like to point out that SiS chipset works faster in this application than VIA KT600.

The situation in Windows Media Encoder 9 is pretty strange. The winner here is SiS748, which managed to outpace even the dual-channel nForce2 Ultra 400 solution.

In Business Winstone 2002 SiS748 again manages to get to real heights. At least it simply ruins VIA KT600. We suppose that SiS748 owes this situation (as well as the victory in the previous test) to the high-quality caching IDE driver supplied by SiS.

The results of Multimedia Content Creation Winstone are quite predictable. As usual, the leader is nForce2 chipset family, then comes VIA KT600 and the last one is SiS748.

In conclusion we would like to offer you SPECviewperf 7.1 results, which are completely different from what we have already observed. However, as we have already mentioned several times, this benchmark models the work in professional OpenGL applications and is very good at indicating the advantages of the memory bus featuring high bandwidth and low latencies. This case is no exception. The dual-channel nForce2 Ultra 400 is the leader here. The single-channel nForce2 400 is a little behind. And the third winner is a real surprise to us: SiS748 managed to outpace VIA KT600 in 4 tests out of five.

Performance at 400MHz Bus Frequency

The second part of our test session will be as exciting as the first one, of course. Here we used AMD Athlon XP 3200+ on Barton core working at the actual 2200MHz frequency and intended for 400MHz bus. Since the fastest AMD processors are intended for this particular bus, this test session will show if the new chipsets are really ready for work with the top AMD CPUs.

Note that here we have a little fewer results than in the previous section, because with 200MHz FSB we didn’t run any tests for platforms with DDR333 SDRAM (slower memory could be the limiting factor here, and not the chipset).

Just like in the previous part of the article we would like to begin the platforms performance analysis with the results of the synthetic Cachemem test:

The shift to faster system bus doesn’t affect the situation. Moreover, the advantages of the nForce2 chipset family become even more evident.

And SiSoft Sandra 2003 shows that VIA KT600 finally manages to defeat the single-channel nForce2 400. I wonder if we will see something like that in real applications...

PCMark2002 returns KT600 to the solid ground. NVIDIA nForce2 400 is very far ahead here. Now let’s turn to real tasks.

3DMark tests showed very common results. First comes the dual-channel NVIDIA nForce2 Ultra 400, and among the single-channel solutions the laurels belong to another NVIDIA offspring. The slowest one here appeared SiS748.

The same situation repeats in real 3D shooters. Note that sometimes the gap between NVIDIA nForce2 chipsets and the competitors from VIA and SiS is more than tremendous. Yes, NVIDIA DASP technology is a really worthy thing. Also we have to point out that SiS748 turned out a stable outsider as soon as we shifted to 400MHz processor bus. Now it is always behind VIA KT600.

The data compression benchmark again demonstrates the brilliant potential of the DASP nForce2. The results of KT600 and SiS&48 are very sad especially against NVIDIA’s background.

Well, the leadership of nForce2 solutions is no news for you. There is another interesting thing worth mentioning: for the first time in the part of our test session with 400MHz processor bus SiS748 outperformed VIA KT600.

 And in Windows Media Encoder 9, SiS748 manages to dash ahead of all, just like in the previous case, when we tested the platforms with 333MHz processor bus.

In Winstone test package SiS748 also is a little faster than VIA KT600 solution. we have already pointed out the possible reasons for this advantage.

In SPECviewperf 7.1 nForce2 Ultra 400 manages to leave everyone else far behind due to its maximum memory bus bandwidth.

Conclusion

Well, let’s sum everything up. First, I would like to point out that we are very unlikely to witness any changes in the Socket A chipset market in the near future. NVIDIA managed not only to stabilize its positions in this segment during the past year, but also became the leader here. As we see, the competitors cannot do anything about it. nForce2 chipsets remain indisputable performance leaders.

Of course, nForce2 does have certain drawbacks, such as the lack of SerialATA protocol support. However, this fact is very unlikely to distract the users’ attention from this chipset family, especially since it is sometimes 10% faster than the competitors. DASP appeared an extremely smart chipset unit, and none of NVIDIA’s competitors managed to offer a worthy alternative to it.

The launch of a single-channel nForce2 400 chipset is a pretty logical move of NVIDIA’s. As we found out, the newcomer is not too much slower than its dual-channel fellow: the performance difference is not more than 2-3%. This is more than enough to make nForce2 400 the fastest single-channel Socket A chipset. So, nForce2 400 has every chance to win a stable leading position in the today’s market, since the competitors are still unable to offer a solution fast enough to defeat the new leader.

Despite aggressive marketing, VIA didn’t succeed with its Socket A solution. After the launch of KT333, the company rolled downhill little by little. KT400A was far from success, and the today’s KT600 seems very unlikely to help VIA regain its leadership in the Socket A chipset market. In reality VIA KT600 appeared considerably slower than NVIDIA nForce2 Ultra 400 and NVIDIA nForce2 400. That is why almost the major advantage of VIA KT600 is an attractive features list including SerialATA HDDs and RAID arrays support.

According to our tests, SiS748 is running almost neck and neck with VIA KT600. That is why this solution has very good chances to win the low-cost platforms market, as SiS is traditionally known for its low prices.

As a result, we would like to recommend all gamers and advanced users who are willing to squeeze the maximum out of their systems to pay special attention to dual-channel NVIDIA nForce2 Ultra 400. If you are not so dedicated and can stand a small performance drop, the single-channel NVIDIA nForce2 400 will be a good choice to think of. The new solutions from VIA and SiS will definitely find their way into low-cost systems. However, you shouldn’t forget that they are considerably slower than NVIDIA’s chipsets. Anyway, a lot will surely depend on the final cost of SiS748, VIA KT600 and NVIDIA nForce2 400.