SiS Xabre 600

By: Dmitry Zinovyev

Price matters more than FPS

Manufacturers can tell whatever tales of how fast a game will fly in 2003 on NV30 or boast hundreds FPS Radeon 9700 Pro today offers. But retail shops have always done and will do best just with on-the-budget solutions like GeForce 4 MX or competing boards. Every manufacturer dreams of biting off a heftier piece of the budget market, and indeed truly serious competition is on the up not about high-end products costing half a thousand bucks but about those whose price tags rank below $200.

The Xabre 600 chip

Two memorable events at once occurred on 25 November. First, it is the Moscow nVidia's live presentation of an NV30 working specimen with a dozen of brilliant demos run on it. Secondly, the information embargo put on SiS Xabre600 is up. This new low-end chip will replace the Xabre 400 covered in enough detail on the 3DNews pages. Before you delve into our Xabre 600 review, take some time running through the following materials:

Testing Xabre 400 video cards
Xabre400 Reference
Elitegroup ECS AG400
Gigabyte SP64D-H
Vinix VX-3340
PowerColor EvilXabre400

Meet Xabre 600

SiS Xabre roadmap

But let's not run forward. Mind you, the manufacturing process is not yet the most important thing. Let's outline the key features of Xabre 600 as compared with the competitors' chips:

Now let's talk a bit about the chip architecture. The flow-block below gives a visual idea of the card's design:

Xabre 600 architecture

Paired with the new chip, the SiS301 provides the TV-out and output to a second monitor in exactly the same manner as Xabre 400 does. We'll provide more details of the chip below.

It makes sense outlining the key technologies used in the Xabre 600. First of all, it's the Vertexlizer Engine, the bandwidth optimization system XmartAGP, the images output control system XmartVision, the chip frequency control XmartDrive and the optimized Xminator II driver. The latter differs from the Xminator II in the support for the above listed technologies.

By sight and on the menu level, the driver does not make any difference to that bundled with the Xabre 400, so we won't dwell on it here. So, let's start telling of the Xabre 600 GPU with the Vertexlizer.

Traditional architecture of vertex shaders

Architecture of the Xabre 600 vertex shaders.

It's almost impossible to find any differences between the two flow blocks supplied with the SiS press kit. Judging by the drawings, the only difference for the case of Xabre 600 is in the name. In fact, the Vertexlizer Engine is a system in charge of the dynamical load distribution in vertex shaders between the GPU and CPU. All this allows SiS to claim - the vertex shader efficiency in Xabre 600 is rising as the CPU clock speeds go up, and at 2.8 GHz its efficiency is very close to that of nVidia GeForce 4 Ti4200:

One may start lengthy reasoning as to whether it is appropriate to use Pentium 4 2.8 GHz for a budget card or not. But that's not the point. SiS decided quite logically that for the budget system it makes sense trying to shift part of the load onto the CPU rather than implementing slow vertex shaders.

Next item on the agenda is the Xmart technology consisting of three components. The first, XmartAGP, is a system that automatically detects the AGP type of the system and based on the data decides which operation mode is the most efficient for the card. The second component is the XmartVision system that determines what the accelerator is doing at a particular moment. If it is busy outputting the 2D graphics in applications not requiring 3D, the system will make the image softer and nicer to the eye, which allows turning down the strain to the eyesight. If you start a 3D application, the driver will turn up the contrast and brightness making the image richer and more distinct. Basically, this resembles the 3Deep or similar utilities. What remains to be done is to verify in action how this technology affects the image quality.

The last Xmart-technology is the XmartDrive. At times when the system does not need maximum performance, the chip switches to the sparing mode and puts the frequency down, which prevents the chip itself from overheating and thus streamlines the system heating. This also increases the stability of both the accelerator and the computer on the whole.

SiS Xabre 600 Reference Layout

We haven't come across such functions on modern cards for quite a long time, the look-and-feel sometimes gives you an impression of the past century rarity. Close to the TV-out there spots for soldering extra elements, which hints to the possibility of chip installation for both the video out and in. On the board there is also the wiring for a feature-connector, which is not implemented physically. The shortcoming of the jumpers is also in the lack of any legible captions, which makes it very difficult to sort out where a certain jumper should be.

Memory

Cooling system

Another piece of news is that you won't get by without skillful hands. There is no sign of any heat-conductive material or thermopaste between the chip and the cooler. It's evidently a sign of useless saving. Anyway, the radiator is pressed quite well to the chip and finely polished, but we believe it won't be enough without thermopaste. The noise levels during the operation are not that high, - moreover, compared with the top-end ATi/nVidia or OTES solutions, the card is almost noiseless.

TV/DVI outputs

A serious drawback of the TV-out which we found out is the impossibility to change the TV standard "on the fly". The idea of reverting to jumpers nowadays sounds a bit weird.

The DVI-out is ordinary, no-frill. You can connect both an LCD panel through the DVI and an ordinary CRT/LCD monitor having an analogous input via an adapter. The card will certainly suit for use with two monitors although its 175 MHz RAMDAC integrated into its companion chip SiS301 is rather weak for displaying the output onto the second monitor.

What especially stands out is the excellent 2D quality on the master monitor. For that price category it is absolutely fantastic, provided the proprietary driver is used. The VESA modes under Windows XP look awful, run in the interlaced mode and are painful to the eyesight.

3D performance

Tests

• Processor Intel Pentium 4 2.8 GHz;
• Memory RDRAM PC800, 512 MB;
• Motherboard Intel 850EMV on the i850E chipset
• Sound card Creative Sound Blaster Audigy;

• 3DMark 2001 SE Pro (Direct3D, synthetic test on the base of the MaxFX core)
• Codecult Creatures Benchmark (Direct3D, a complex test that efficiently involves the AGP part)
• Unreal Tournament 2003 Demo (Direct3D, real-life stress test benchmark);
• Return to Castle Wolfenstein (OpenGL, on the Quake 3 engine).

As the resolution goes up, the Xabre 600 starts taking a noticeable lead over Xabre 400. We'll analyze what contributes to this through comparison of separate components of the suite:

First off, note the fill rate which is one of the most important parameters especially for the old games having no support for shaders, T&L and other new technologies, that is games which shift solely the rasterization onto the accelerator.

At the multi-texturing speed with and without it, the Xabre 600 is much faster than Xabre 400. On the average, the card displays approximately a 20% performance boost. We believe this is related primarily to the increased chip and memory speeds, that is, through overclocking the Xabre 400 you might get some similarity in results for this test.

Another important benchmark is the vertex shader performance. As you remember from the introduction to this review, SiS claimed to have added the Vertexlizer system into Xabre 600, which is meant to distribute vertex shader loads between the graphics chip and the CPU. Unlike the pixel shaders, vertex shaders can be quite easily handled by the CPU. In the end, this gave a not too bad result after all - the speed of handling the vertex shaders in Xabre 600 is often much higher than in GeForce 3. Subsequently, we'll try to prepare a detailed research on Xabre 600 vertex shader performance vs. the processor used.

The last noteworthy benchmark is Nature in which both vertex and pixel shaders as well as many other secondary rendering technologies are in abundance. Evidently, Xabre 600 is not strong enough to contend with nVidia's high-end products, but it does make a big difference from the past generation products already at the start, and as the resolution goes up, the performance difference may be as high as 50%.

Now on to the Codecult benchmark. This is an extremely resource-hungry benchmark, very critical to the memory capacity and other system characteristics. If you look at the upper graph of common results, you can't help seeing that it's the 128 MB video cards that are ahead of the pack at performance. Specifically to Xabre 600, there is an evident lag past GeForce 3. We won't bring in the benchmarking results for Xabre 400 any further, since they are visibly worse, and the benchmark runs extremely slow with this card. In this connection, it's worth recalling a recent scandal when SiS was blamed for overstating 3DMark 2001 scores. The experiment was very simple - colleagues from the iXBT site removed any mention of the 3DMark test, renamed the *.exe file and started tests. The results were much lower than those produced at the original test setup, which led to a conclusion that SiS had somehow modified the driver to get higher scores on this popular benchmark.

Finally, the gaming benchmarks - Unreal Tournament 2003 Demo and Return to Castle Wolfenstein. Here you can't cheat the counter that easy. There is an interesting evidence - in RTCW, the card in some scenes attains a 3-fold (and even higher) lead over Xabre 400, especially at higher resolutions, but in Unreal Tournament it's not much better at FPS than Xabre 400.

Wrapping it up with the benchmarks, it's worth noting that things differs greatly in different games and benchmarks. We can claim with confidence that Xabre 600 is faster than Xabre 400, and in most benchmarks the attained lead is quite substantial. Along with that, at performance the card sometimes is close to the much more expensive GeForce 3, in some benchmarks it showed even a bit better than GF3. This is a definite bonus for a budget product.

Findings

Pros:

• Excellent 2D quality;
• Support for two monitors;
• Operational stability;
• Low price.

Cons:

• Outdated switching between TV standards;
• Illegible captions under the jumpers;
• No thermopaste under the cooler.

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