SiS Xabre Preview June 26, 2002 Brandon Bell

Introduction

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While we all dream of 300MHz+ GPUs with 128MB (or more) of ultra-fast DDR memory, not everyone has the disposable income to afford this. Graphics processor manufacturers know this as well. These manufacturers break the market up into three segments: value, (graphics cards below $150 – although this number has quickly faded to the $100 mark on the street) mainstream (cards around the $200 price point), and enthusiast ($250 and up).

The enthusiast market is where all the buzz and marketing takes place. Bragging rights are crucial in this segment, if you have the hottest card in this space, not only will you have a product consumer’s lust over, you’ll also have a line of enthusiasts willing to pony up the dough to get it. And while the market itself is composed of a select (read: small) group of consumers, the profit margins for these cards aren’t.

On the opposite end of the spectrum is the value segment. Profit margins here are incredibly slimmer, but at the same time the market itself is considerably larger – not only are consumers interested in saving a buck, so are tier one OEMs such as Dell and Compaq. As a result, manufacturers such as ATI and NVIDIA must play a balancing act between all three segments – slip a few too many features in a value card and the mainstream market can dry up, or the price on your enthusiast card could be so high that most consumers pass it up.

Maintaining the proper balance was traditionally obtained by slipping in newer, faster products to replace the older variant. An example of this would be 3dfx’s Voodoo2 replacing the original Voodoo Graphics card in the enthusiast segment as the Voodoo1 shifted to the value market. More recently graphics manufacturers have been releasing cores at different clock speeds – the faster cores simply cost more money. In the case of the value segment, this is also coupled with a less powerful graphics core.

It is partially because of this strategy that smaller players in the graphics field have been able to sneak their way into the value space while the big boys are focused on trumping up their products at the top. Last summer ST Microelectronics and PowerVR teamed up with Hercules (among other manufacturers) to deliver the Kyro 2. While it generated an enormous amount of fanfare when it was launched (and spurred NVIDIA price cuts) Kyro 2 ultimately was forgotten when ATI and NVIDIA refreshed their product lineups in the field.

This summer another player has arrived to duke it out in the value space: SiS’s Xabre line of graphics cores.





SIDEBAR: SiS Xabre Product Webpage

Specifications

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The list

Pixelize engine

Notes

If you recall our original GeForce4 preview, the biggest complaint we had with the GeForce4 MX was its omission of a dedicated hardware pixel shader – this function was left to the system CPU. With Xabre, all that has changed. Unlike the GeForce4 MX or RADEON 7500, the Xabre graphics processor has a built-in pixel shader making it the first DirectX 8-compliant video card in the value segment.

Another first with Xabre is its support for AGP 8x operation. Once installed, the GPU auto-detects the proper AGP mode, ensuring optimum performance without any involvement from the end user.

Besides the integrated pixel shader, Xabre also has another advantage over GeForce4 MX in terms of fill rate. With its quad-pixel pipeline, Xabre 400 has a peak fill rate of 1.0 (4 pixels per clock x 250MHz) billion pixels/sec. In comparison, GeForce4 MX 460 only features a dual-pixel pipeline providing a fill rate of 600 Mpixels/sec (just under twice the fill rate of GeForce2 MX). In addition to its quad pixel pipeline, Xabre is able to process eight textures per pixel pipeline for eight texels per clock, equating to a fill rate of 2 billion texels/sec to GeForce4 MX’s 1.2 billion texels/sec. In terms of memory bandwidth however, the edge goes back to GeForce4 MX 460: 8.8GB/sec versus 8.0GB/sec (although Xabre can support twice as much memory as GeForce4 MX).






SIDEBAR: SiS’s Xabre GPU was officially launched April 24th of this year.

More Xabre details

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Three Xabre’s to choose from

Like the GeForce4 MX, three versions of the Xabre are set for production. At the top of the list is the Xabre 400. As we mentioned earlier, Xabre 400’s core clock operates at 250MHz. Likewise, its DDR memory also runs at 250MHz. This puts the Xabre 400 slightly below the GeForce4 MX 460 (300/275) and very close to the GeForce4 MX 440 (270/200MHz) in terms of pure clock speeds, but as we mentioned previously Xabre has the edge in pixel pipelines, resulting in a fill rate edge for SiS’s chip.

Personally, we were a bit surprised at the conservative clock speeds for Xabre 400. As an upstart that was intended to compete with the well-established MX line, we felt SiS should have gone out on more of a limb with Xabre. Xabre is built off of SiS’s own 0.15-micron manufacturing process, but we were never given a transistor count for Xabre so we’re unsure how complex its design is. Perhaps it just boasts too many transistors to generate the yields SiS is looking for. Ultimately it will be up to the overclocking community to see what Xabre can really do.

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Visual Quality/Compatibility

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Visual Quality

First off, we must state that a topic like the visual quality of a particular video card is highly subjective: what might look beautiful to one person’s eyes may be atrocious to another person. Another item to keep in mind is that our Xabre 400 board is a reference card provided by SiS, therefore our results may be different than retail boards from actual card manufacturers.

With all that being said, in terms of 2D visual quality, SiS’s Xabre 400 was right up there with the RADEON 7500 and VisionTek Xtasy MX 440. We ran our tests with a 21” Sony G500 monitor running at 1920x1440 resolution with 32-bit color. We noticed that the Xabre 400 doesn’t support quite as many resolutions in the upper realm of displays as the ATI or VisionTek cards, although this can be fixed quite easily with a new driver. The Xabre and RADEON 7500 displays looked remarkably similar in Windows XP, we’d be hard pressed to see the difference between either card in a blind “taste” test. Text was nice and sharp (even at the edges), and images were never blurry. The VisionTek card would also rate as an “A” although it may fall just a percentage point (or two) behind the others. One positive going for the VisionTek that we really liked: the drop shadows behind desktop icons in Windows XP were more pronounced than the other two when using the default “Bliss” background.

In terms of 3D visual quality, we found this to be a mixed bag. In games that Xabre runs well with (practically any Quake 3 engine game) visual quality is excellent. Xabre’s Coloredeemer technology does a very good job of optimizing color, in addition Xabre has built-in tools that automatically adjusts gamma and makes brightness adjustments on the fly. Anyone that remembers the early days of 3D can attest to the gamma problems NVIDIA’s original RIVA cards suffered from. These problems weren’t present in any of the games we tested Xabre with.

However, errors did crop up with Xabre in Serious Sam 2. Textures on tree leaves were over saturated at long distances, but cleared up once your character got closer. Image quality was great in 3DMark 2001 SE, although stability wasn’t flawless. Speaking of stability issues, we had lots of stability problems with Xabre and Serious Sam 2 as well as Codecreatures syntetic benchmark. We would rate these two applications as the most unstable, and we’ve heard of issues with DroneZ as well.

Compatibility

System comp ability with Xabre also needs a little more work. While Xabre runs fine on Intel and SiS-based platforms, we couldn’t get our Xabre 400 card to run in AGP 4X mode with any of our VIA-based motherboards (performance was still good despite this). Xabre’s predecessor also had problems with VIA-based chipsets, so we weren’t surprised that problems still existed with Xabre. What really surprised us was that stability varied from motherboard to motherboard. Therefore we have a very sneaky suspicion that SiS isn’t the only party to blame.





SIDEBAR: SiS has provided a webpage with a list of recommended games.

System Setup

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Intel Pentium 4 2.2GHz

ASUS P4B266

256MB PC2100 CAS2 DDR SDRAM

ATI RADEON 7500
Driver version Catalyst 6.13.10.6094
NVIDIA GeForce4 MX 460
NVIDIA GeForce4 MX 440
NVIDIA GeForce4 MX 420
Driver version Detonator 28.32
SiS Xabre 400
Driver version 3.02a.02

30GB IBM Deskstar DTLA 307030 ATA/100 Hard Drive
AFREEY 12X DVD-ROM

Windows XP Professional

DirectX 8.1

Desktop Resolution: 1024x768x32

Benchmarks

3DMark 2001 Second Edition w/ 330 patch - 32-bit color, 32-bit textures
Quake 3 Retail - High Quality
Serious Sam: The Second Encounter - Normal (32-bit) The Elephant Atrium demo
Jedi Knight II – Normal Quality



SIDEBAR: The Xabre reference board shipped with 3.3ns memory from Etron Tech.

3DMark 2001

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3DMark 2001 - DirectX 8

Analysis

Xabre 400 holds the performance advantage in 3DMark 2001 SE, at 800x600x32 Xabre outperforms GeForce4 MX 460 by 11% and RADEON 7500 by 15%. As the screen resolution increases and the demand on the graphics subsystem increases, the margins close.

We feel a large reason the Xabre 400 finishes first in this test is because of its built-in pixel shader – quite simply it’s the only card in this comparison that can perform the nature test, and therefore it gets a higher overall 3DMark 2001 score. Lets take a closer look at the frame rates to confirm or deny this.



SIDEBAR: Our Xabre board was clock locked from the factory, no overclocking allowed.

3DMark2001 Framerates

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3DMark 2001 - Car Chase

3DMark 2001 - Dragothic

3DMark 2001 - Lobby

3DMark 2001 - Nature

Analysis

In low detail situations, the Xabre finishes first or second in all 3DMark 2001 tests at 1024x768x32 (although its virtually tied in two of three tests). We feel a large part of this could be due to its superior fill rate. Once the graphics core and its memory are put under greater stress the final results are a bit more mixed, with the Xabre 400 giving an impressive performance for an upstart. And of course, with its hardware pixel shader, Xabre 400 is the only card in this article capable of running 3DMark 2001’s nature demo, giving it longer legs than the other cards in DirectX 8 games.



SIDEBAR: SiS is aiming to keep Xabre price competitive with GeForce4 MX 440. That would put it in the $100 price range.

Serious Sam 2

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Serious Sam 2 - OpenGL

Analysis

As we mentioned earlier, the Xabre 400 has some compatibility issues with Croteam’s Serious Sam 2, and they’re not just related to stability. Performance wasn’t on par with the other GeForce4 MX boards or the RADEON 7500, SiS’s Xabre 400 finishes 19% behind GeForce4 MX 460 and 14% behind RADEON 7500 at 800x600x32. As the screen resolution increases, the gap widens even more.


SIDEBAR: Our Xabre reference board was revision A1.

Quake III

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Quake III - High Quality

Analysis

In Quake 3 Xabre 400 fares much better, finishing six percentage points behind GeForce4 MX 460 and holds a slim two percent advantage over GeForce4 MX 440. MX 460 is able to obtain a little more breathing room at higher resolutions, while the MX 440 falls behind, and then catches up again at 1600x1200. This is surprising considering the fill rate and bandwidth advantages held by Xabre 400 over GeForce4 MX 440.


SIDEBAR: We were told that Xabre boards would be available by this time, but this obviously isn’t the case. Hopefully SiS is taking the time to polish the drivers a bit more.

Jedi Knight II

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Jedi Knight II

Analysis

We witnessed a really interesting paradox in Jedi Knight II, at the lower resolutions Xabre’s performance remains unchanged for the most part, then really outshines the competition at 1600x1200. To us, this really looks like the Xabre’s drivers need more work in Jedi Knight II.



SIDEBAR: SiS has publicly committed to releasing a Xabre follow-up (Xabre 600) in ‘Q3 of this year with a faster clock rate (275/300). Their DX9 board (Xabre II) is due in the first quarter of next year.

Conclusion

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Final thoughts

While Xabre isn’t SiS’s first graphics product, this is the first time in quite awhile that SiS has attempted to launch a new graphics core with so much potential (in comparison to its competition) as well as fan fare. Quite simply, on paper the Xabre delivers. Not only does it boast a more powerful 3D engine, thanks to its integrated pixel shader Xabre also offers more headroom for the future than any other card in its class.

This results in a mixed bag of performance so far. In tried and true applications (Quake 3 and 3DMark 2001), Xabre performs very well in comparison to its competition. However, there are other applications (Serious Sam 2 in particular) that need quite a bit more work.

In the past month, SiS has released three new driver revisions for Xabre, each one bringing greater performance and game compatibility. While this relentless effort to improve Xabre definitely deserves to be admired, as it stands now we can’t quite recommend Xabre to end users at this point. Compatibility with Intel systems is excellent, but VIA-based system (which represent the bulk of systems built with AMD processors) compatibility is hit and miss. This situation alone makes us quite skeptical, making it worse is the compatibility issues that exist with some games. As we mentioned earlier in this review, game compatibility issues are nothing new for an upstart in the graphics market – even NVIDIA had its fair share of growing pains early on. It’s what SiS does from here that will determine how successful a product Xabre becomes. If getting the compatibility bugs squashed isn’t a hard enough task, obtaining solid distribution channels (especially in the US market) should be more than enough to keep SiS busy for now.

While SiS succeed or fail? Right now it’s too early to say. The performance potential is definitely there (just look at 3DMark 2001 SE); SiS just needs to polish their drivers just a bit more. Once that is done Xabre could be primed to steal lots of sales from ATI and NVIDIA but it won’t be an easy task to accomplish.


SIDEBAR: What do you think of Xabre? Does it have potential, or should SiS stick with system chipsets? Voice your thoughts in the comments!