When we think of SiS graphics, we usually think of low cost, low-end cards or integrated offerings for the entry-level 2D market, with the possibility of some rudimentary 3D capabilities thrown in. SiS graphics chips have traditionally been for systems where graphics performance isnt a key marketing decision, but the new Xabre GPU could herald a change in attitudes towards the company. Its a chip that ups the performance of previous SiS graphics offerings, yet holds onto the value pricing.

The Xabre is being aggressively marketed, with the promotions ramping up as more and more manufacturers release products based on the chips. Only the Xabre400 will be initially released, with three more flavours to come: the Xabre600, Xabre200 and Xabre80. SiS has a decent number of big manufacturers lining up to produce Xabre-based cards, such as Gigabyte, Gainward, Chaintech, Jaton, Joytech, Transcend and more.

One of the features heavily promoted in the Xabre advertising material is 8x8, which refers to the main selling points of the graphics cards. 8X8 stands for the two main features: its full DirectX 8.1 compliance and status as the worlds first AGP 8x graphics card.

Theoretically, AGP 8x increases the video bandwidth from AGPs 4x 1GB per second to 2.1GB per second. Those are some fairly impressive numbers to be throwing about, but the reality is that there arent that many AGP 8x motherboards on the market yet. And even if you do buy an AGP 8x capable motherboard, its highly unlikely that youre going to squeeze much more performance out of your system by installing an 8x graphics card because no program is really going to be using that bandwidth for quite some time. When the applications and games do advance, however, APG 8x will become a necessary and ubiquitous feature of future graphics cards and motherboards.

The second selling point, the DirectX 8.1 compliance, is an extremely important feature, as most of the Xabre card manufacturers will be positioning their cards against their own and other competitors GeForce4 MX graphics cards. The GeForce4 MX was the notoriously pared-down version of the GeForce4 line, which lacked a full set of the DirectX 8.1 pixel-shading functions. This meant that when testing the card with MadOnions industry standard 3D benchmark, 3DMark2001 SE, the GeForce4 MX cards could not run every test in the suite. The Xabre400 on the other hand, has support for all DirectX 8.1 functions and aside from some driver issues (see below), it ran the tests fine.

The new technologies in the chip include a Pixelizer Engine, which is made up of hardware pixel shaders with 29 programmable instructions, a 3rd generation hardware T&L engine with a 16 vertex cache, and vertex shading support. This latter is responsible for the only performance bottleneck with the Xabre (depending on what program youre running), as Xabre400 lacks hardware vertex shaders, it uses software shaders with the CPU running hardware emulation.

The card also features the FMC (Frictionless Memory Controller), which is a way for SiS to streamline memory usage and up the memory bandwidth on the card, and a Motionfixing Video Processor that is responsible for removing artefacts and smoothing out video when watching DVDs or MPEG movies. It also features Jitter-Free AntiAliasing at 1x, 2x and 4x full-scene to remove jaggies, and Double Scene Technology for outputting to dual displays.

Pitched where its at
We got hold of two Xabre400 cards: one an early engineering sample from SiS, the other a pre-production Triplex Millennium Silver Xabre400 Pro model from up-and-comer Triplex. The SiS engineering sample was so early in fact, that that the heatsink didnt fit flush against the GPU because of an overly ambitious capacitor. We werent too keen on running the card without the heatsink fitted properly, so we removed it, brought it down the road to the local welders workshop and took to it with a hacksaw. A few minutes later and the newly MacGyvered card was up and running happily, with the heatsink sucking away the extra degrees of heat.

Initially, we liked the performance of the SiS card but were deterred by the fact that the card itself made a considerable audible noise whenever you asked it to do hefty 3D work, such as when running a benchmark. This is a problem with the extremely early cards, and according to SiS, has been identified as a faulty L10 inductor, which has been rectified for all consumer models to come. This was apparent with the Triplex card that featured a considerably pared down PCB but was silent when being benchmarked.

We ran the cards on an Intel i850E reference board, with a 2.4GHz Pentium 4 at 533MHz FSB, with 256MB RDRAM. Even though its a reference board, its been one of the more stable motherboards to pass through our testing Labs in some time. Its also an AGP 4x motherboard, but we tested with this because the only boards out there now that support 8x AGP are VIA boards, and there are severe performance problems with VIA chipsets and the Xabre GPU at the moment. Look for 8x AGP tests in the coming months as commercial Xabre cards and AGP 8x motherboards get released, and the VIA/Xabre driver issues are fixed.

We benchmarked the Xabre400s with the latest reference drivers from SiS (version 3.02.53), a patched version of 3DMark2001 SE (which allows the benchmark to properly recognise the Xabre chip), and compared the two Xabre cards against a GeForce4 Ti 4200, a GeForce4 MX 440 and a GeForce4 MX 460 on the same machine.

So is the Xabre a GeForce4 killer? No, not at all where the GeForce4 Ti range is concerned, however it smacks the pants off the GeForce4 MX range of cards. This is evident with the 3DMark2001 SE benchmarks, where the Xabre400 is much higher than even the MX 460 card, but just below the Ti 4200.

Have a look at the framerates for Quake 3: Arena, and youll notice the Xabre drops a little. We feel this is more a driver issue than something wrong with the card, although we did note differing video quality depending on the programs we ran on the card.

Now, for the punchline: the Xabre400 with 64MB 3.3ns DDR is going to be priced around the $199 mark at launch, which is extremely affordable for a card of this calibre. The current drivers are not very mature, although more stable and higher performing drivers are sure to be released shortly. At this price, and with this performance, theres no reason for you to not consider buying a retail Xabre graphics card.