VIA had the honour to announce the first DDR chipset for Pentium 4 with its semi-legal P4X266. SiS had a lot of innovations too, like the FireWire MAC controller integrated in the south bridge. And of course, Intel announced a lot of novelties as well. In the spring of 2003, i875P and then i865PE chipsets appeared and remained unachievable for all their rivals in terms of performance. As for the functionality, it wasn't until last autumn that SiS and VIA caught up with them. We are not taking ALi into account as ALi 1683 has a very poor functionality and a very low performance. ATI's first more or less successful desktop chipset (Radeon 9100 IGP) is a long way from i865PE in what concerns performance of discrete work (which can't be said about its graphic core performance compared to i865G). Besides, ATI south bridges look really deplorable. And now, a year later, the market sees a pile of boards based on modern dual-channel Taiwanese chipsets. Will they surmount the 865/875 height?

SiS655TX

SiS655TX crowns the current line of SiS chipsets for Pentium 4, as it has the richest functionality (though it doesn't differ from SiS655FX in this aspect) and [presumably] the highest performance. Let us look at its functional scheme:

All the things we said about SiS655FX in our previous article hold good here, so we'll only enumerate its capabilities briefly:

• support of 400/533/800MHz CPU bus;
• dual-channel DDR266/333/400 memory controller (up to 4 modules/4 GB);
• AGP 4x/8x bus for external videoaccelerators;
• MuTIOL 1G bus (~1 GB/sec bandwidth) down to the south bridge;
• SiS964 south bridge;
• 2 IDE channels for 4 UATA66/100/133 devices;
• 2 SATA ports for 2 devices with RAID (0, 1, JBOD) function;
• 8 USB 2.0 ports;
• up to 6 PCI Bus Master devices;
• AC'97 interface for 6-channel audio codecs;
• Fast Ethernet MAC controller (up to 100 Mbit/sec);
• support of low-speed peripherals.

Both bridges have almost standard functionalities today and feature no "luxuries", such as integrated FireWire or Gigabit Ethernet controller. The company is certainly planning to introduce the support of PCI Express and DDR2, but there's no information as to when SiS656-based products will appear on the market. In fact, SiS655TX+SiS964 is all but a spitting image of i865PE/i875P+ICH5R, the only difference being that the former appeared a year later.

  

SiS655TX has a feature that fits very well its low price: the chipset allows to apply the dual-channel mode not only to two/four identical DIMMs (as is the case with other dual-channel solutions including those by Intel and VIA), but also to unsymmetrical pairs, and even to three modules. Thus, SiS655TX-based boards keep their advantage over single-channel chipsets in terms of performance, but provide users with more flexibility and save them the trouble of choosing an operable pair of DIMMs for the dual-channel mode.

The promised difference from SiS655FX consists in a revised memory controller. The new technology is called Advanced HyperStreaming. But if we visit the company's site, we can read that the Advanced HyperStreaming Technology in SiS655TX "enhances the transfer rate on the path from host block to memory controller block". Does that ring any bell to you? It definitely reminds us of last-year press releases made by Intel (about its i875P) and mainboard manufacturers (concerning their own acceleration technologies in i865PE-based boards). But instead of going on repeating about this "coincidence", we'll try to estimate once again how much SiS655TX is better than its predecessor and if the couple can compete with i865PE/i875P.

VIA PT880

PT880 is VIA's first ever dual-channel chipset (KT880 has been announced but obviously, we'll have to wait for boards based on it to appear). PT800, its predecessor, though having set no performance records, showed a surprisingly good functionality that could compete (and how) with top rival products. Nothing except the memory controller has been revised in this VIA chipset, so the functional scheme of PT880 must seem familiar to you:

These are PT880 capabilities, in brief:

• support of 400/533/800MHz CPU bus;
• dual-channel DDR266/333/400 memory controller (up to 4 modules/8 GB with ECC supported);
• AGP 4x/8x bus for external videoaccelerators;
• Ultra V-Link bus (~1 GB/sec bandwidth) down to the south bridge;
• VIA VT8237 south bridge;
• 2 IDE channels for 4 UATA66/100/133 devices;
• 2 SATA ports for 2 devices with RAID (0, 1, JBOD) function;
• 8 USB 2.0 ports;
• up to 6 PCI Bus Master devices;
• AC'97 interface for 6-channel audio codecs;
• Fast Ethernet MAC controller (up to 100 Mbit/sec);
• support of low-speed peripherals.

  

You have to take a really powerful magnifier to see the differences from rivals' solutions. The PT800/880 memory controller supports twice as much memory and modules with ECC. The VIA chipset has no integrated FireWire or Gigabit Ethernet controllers, and it won't be before the company's next product (PT890) appears that PCI Express and DDR2 will be supported. The only functional difference between PT880 and PT800 except the number of memory controller channels is that the newer one uses a twice faster Ultra V-Link bus to the south bridge. But why should one increase the bus's bandwidth up to ~1 GB/sec is anyone's guess.

Performance

Testbed:

• CPU: Intel Pentium 4 3.2 GHz (16x200 MHz), Socket 478
• Mainboards:
  • ASUS P4R800-V Deluxe (version BIOS 1006) on ATI Radeon 9100 IGP
  • ASUS P4P800 SE (version BIOS 1002) on Intel 865PE
  • ASUS P4S800D Deluxe (version BIOS 1002) on SiS655FX
  • ASUS P4S800D-E Deluxe (version BIOS 1003 beta 001) on SiS655TX
  • Soltek PT880Pro-FGR (version BIOS M1.1) on VIA PT880

• RAM: 2x256 MB PC3200(DDR400) DDR SDRAM DIMM TwinMOS, CL 2
• Videocard: Manli ATI Radeon 9800 Pro 256 MMB
• HDD: Western Digital WD360 (SATA), 10000 RPM

Software:

OSs and drivers:

• Windows XP Professional SP1
• DirectX 9.0b
• ATI SMBus Driver 5.10.1000.2b
• ATI GART Driver 1007b
• Intel Chipset Software Installation Utility 5.1.1.1002
• SiS AGP Driver 1.17
• SiS IDE Driver 2.04a
• SiS SATA Driver 1.05
• VIA Hyperion 4.51
• VIA SATA Driver 2.10a
• ATI Catalyst 4.2

Test applications:

• CacheBurst32 0.91.07
• 7-Zip 3.13
• WinRAR 3.30
• Canopus ProCoder (Demo v1.25)
• Adobe Photoshop 7.0
• Gray Matter Studios & Nerve Software Return to Castle Wolfenstein v1.1
• Croteam/GodGames Serious Sam: The Second Encounter v1.07
• Digital Extremes/Epic Games/Atari Unreal Tournament 2003 v2225

Conclusions

In brief, SiS655TX and VIA PT880 can be quite competitive with top Intel chipsets. The problem is, though, that SiS and VIA introduced their dual-channel solutions almost a year after i865PE/i875P appeared. Moreover, neither chipset offers anything really unique or useful for customers and both SiS655TX and VIA PT880 have worse speed results than Intel solutions do: 5 and 10 percent lower (respectively) in real applications. But of course, Taiwanese companies are likely to set lower prices for their products, as usual, which will help them to win back part of the market.

Speaking about the future, new Intel products codenamed Alderwood and Grantsdale are about to be released, while it is still unclear when SiS and VIA will be able to offer chipsets supporting DDR2 and PCIE. And although it is very doubtful whether end users will really need DDR2 (or, to be precise, current revisions of this memory type), there seems to be no stopping PCI Express now. Thus, we can face an already-seen situation where Intel sets the yardstick and others try to qualify for it. Well, we won't have to wait long to see what it all will be like in reality.

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