by FastSite
06/25/2002 | 12:00 AM
For 500 years, demons tyrannized the world of human vision with omnipresent control. The demons competed among themselves, and the winner set the rules for domineering the world of human vision while human beings paid a high price for their enjoyment.
In the midst of all the chaos, the people began to pray for the arrival of the mysterious knight, whom legend had it would end the strife and rejuvenate the visual world.
And so it happened that a mysterious knight - Xabre - did appear at this time. He understood the people's suffering under the demons' tyranny. He knew what the people needed and secretly began breeding a magical steed that could race across the sky. During his quest, he also found three lost sacred stones - Pixelizer Engine, Software Shader and Frictionless Memory Control, each with wondrous powers.
With these treasures, Xabre entered the forest of visual fantasy bordering the land of the demons, where he discovered the 8X8 twin sword. The one-and-only twin sword in the world was stuck in a cold and hard rock so big that no ordinary human being could pull it out. Xabre knew that without this magical weapon he would not be able to defeat the demons. And so he gathered all the wisdom and power of the people and withdrew the sword from the rock.
Then, without hesitation, he went into the demons' land and defeated them one by one to create a new visual paradise for the people.
This romantic story available on the official Xabre web-site as well as the site itself prove that SiS Company approached the promotion of its new graphics core very seriously. This site offers you a detailed description of the Xabre family, all the official announcements and press-releases, drivers, demo-versions of many games, 3D glossary, FAQ and many other info.
The fact that they tackled this problem so seriously is slightly shocking and makes a really pleasing impression that Silicon Integrated Systems has finally decided to settle in the graphics chips market, and its Xabre chip is the first herald of the coming changes.
You probably wonder what changes we are talking about? Well, I believe we shouldn't remind you of the reputation the previous generation SiS graphics chips have acquired by now. In many respects it is well-deserved, in some respects - not really (for instance, SiS315 is a pretty nice chip with acceptable drivers, see our SiS315 Graphics Chip Review). However, with the launching of Xabre the company seems to be about to change everything completely.
Well, let's see what weapons has Xabre The Brave brought with him to the land of demons :)
Key specifications of the new Xabre GPU:
2D part:
Some features implemented in Xabre chip acquired new unique names:
So, if we do not consider the performance of some particular functions, Xabre doesn't seem to yield a lot to NVIDIA GeForce3 Ti/GeForce4 Ti and ATI RADEON 8500. Its only weaknesses against the background of stronger competitors are: no support of Vertex Shader, anisotropic filtering and such specific features as multisampling by NVIDIA's solution or TruForm and Pixel Shaders ver. 1.4 by ATI's chips.
This "semi-functionality" of the new Xabre chip is an excellent move on SiS' part. If the newcomer is simply unable to support multisampling or TruForm, then the vertex Shaders can be performed by the system CPU. As a result, all DirectX 8 games should ideally be able to run on Xabre without any problems (we will see later in this review how the things actually stand in reality). And SiS could save time and money implementing the Vertex Shader and this way reduce the chip production cost.
Among low-cost chips Xabre stands out due to its fully-fledged support of Pixel Shader ver. 1.3, which allows us to call it DirectX 8 compatible accelerator (remember about the possible emulation of the vertex shader). It appears to be the only accelerator of the kind among the low-cost solutions from ATI and NVIDIA today.
The interesting thing about it is that SiS, which has taken over the current leaders' habit of introducing chip families and not single chips, positions Xabre for three market segments at a time: high-performance gaming market, mainstream market and value market:
This is a very beautiful picture, however, there is a slight shift in the reference frame. The "performance" sector for SiS seems to be more like a "Mainstream" sector for ATI and NVIDIA. And SiS' "Mainstream" sector corresponds mostly to the Value solutions from ATI and NVIDIA. "Value" from SiS is analogous to "Low-End" from the today's graphics industry leaders.
Xabre family currently includes 3 chips (but later one more Xabre 600 working at 275MHz chip and 600MHz (300MHz DDR) memory frequencies will join them):
Today we are going to talk about the fastest model in the family - Xabre 400.
We were very lucky to get our hands on the first pre-production retail sample from Elitegroup based on the new SiS Xabre 400 chip: ECS AG400. It became another guinea pig in our lab this time together with the reference graphics card from SiS.
AG400 graphics cards from ECS will be shipped in a nicely designed colorful retail box:
The card itself is designed on a medium size yellow PCB and doesn't boast any outstanding shapes or components onboard:
The design of the retail AG400 differs noticeably from the SiS's own reference design. Although the reference card doesn't boast an RCA connector for the TV-Out and a port for stereoscopic glasses, it has a luxurious heatsink of unusual shape and unique purple colour :)
Both graphics cards are built on SiS Xabre 400 chip, which looks a bit bigger than NVIDIA GeForce3/GeForce4 or ATI RADEON 8500 and like the latter, features a heat-conducting metal cover:
Both graphics cards are equipped with 64MB DDR SDRAM from EtronTech with 3.3ns access time:
The graphics core and the memory of the solutions considered work at 250MHz and 500MHz (250MHz DDR) respectively.
The cards are also equipped with a special SiS301 companion-chip responsible for the output to secondary display devices, namely for the implementation of TV-Out, DVI and VGA outs as well as for the stereo glasses support:
For our experiments we assembled the following testbed:
Software:
We ran these applications in the following modes:
32bit frame buffer, 32bit textures and 32 (24) bit Z-buffer, D3D Hardware T&L/Pure Hardware T&L.
32bit colour depth, maximum image quality settings.
32bit colour and textures. Maximum quality settings. Tri-linear filtering and texture compression enabled.
Speed Mode: 32bit colour depth. "Speed" image quality settings.
Quality mode: 32bit colour depth. "Quality" image quality settings.
After installing the Windows XP driver, we saw an additional page in the Display Properties - SiS Utility Manager:
From the SiS Utility Manager you can access the control window for setting the display modes in multi-monitor configurations:
Also you can access the desktop gamma correction settings:
…overlay colours settings:
… and the information page:
Besides the additional page in the Display Properties, there appears a special Utility Tray icon in the system tray, which allows accessing all these functions much faster by simply clocking on it:
SiS drivers also include a special 3D Wizard utility, which seems the most interesting to us.
3D Wizard allows controlling the image display in stereo mode (!):
…allows enabling "transparency" (!!!) and wireframe modes in games:
… allows enabling full-scene anti-aliasing (yes! It finally happened: SiS allows the users to adjust the cards accordingly):
… and they even allow the users to overclock their graphics cards easily (no comments here, only exclamation marks !!! :)
Well, frankly speaking, I did hope that SiS would finally introduce something to allow changing the settings for their Xabre cards, but I couldn't even imagine that there would be so many cool things implemented at a time! And the most important thing is that everything does work: anti-aliasing, stereo modes, "transparent walls". The latter works only in Direct3D, though, but I think SiS will quickly improve the drivers, after this really great start.
And in the meanwhile enjoy a pleasing sight from Dragothic test with "transparent walls":
… or a shot from Nature in wireframe mode:
The last utility in the list is AGP Information, which only task is to show the AGP mode the card is currently working in:
The default filtering quality of SiS Xabre has every reason to be called awful. The level of detail (LOD) is too low compared with that by ATI and NVIDIA chips, the image suffers from terrible "ripples" and "seeming double" or simply missing pixels. Moreover, enabling tri-linear filtering in applications doesn't seem to work: there is no tri-linear filtering at all.
I will not load the article with the screenshots of all these horrors, I will just give you a couple of most vivid examples from the Serious Same: The Second Encounter game. On the left you can see bi-linear filtering performed by Xabre and on the right - normal bi-linear filtering in the same scene and testing conditions:
 |  | |
| Bi-linear filtering by SiS Xabre | Normal bi-linear filtering |
You can clearly see that starting from a certain MIP-level, Xabre implements some poor quality approximation instead of bi-linear filtering on a half of each MIP-level.
But this is not the end. Those halves of MIP-levels, which seem to have better quality, also cannot boast "fair" texture filtering: Xabre draws two pixels in a row with the same colour this way trying to save time and trouble processing extra texture samples and applying bi-linear filtering to them. This "doubling" is very noticeable: on the left you can see a screenshot with bi-linear filtering performed by Xabre and on the right - the same scene with coloured MIP-levels:
 |  | |
| Bi-linear filtering by SiS Xabre | Same scene with coloured MIP-levels |
Do you like it? I don't, actually.
Luckily, Xabre still does support some better quality texture filtering modes. When studying the drivers I came across the following section in the registry: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Video\{4EF3E084-AFC7-4AE5-9AB3-EB7231C834D8}\0000, where all Xabre drivers and utilities save their working settings:
This sections has a DWORD key responsible for the "speed-to-quality" ratio during texture filtering: SiS.3D.TexTurboMode. This key is set to 3 as default, and the image "quality" in this case has been already demonstrated above.
I managed to find two more working modes for this key: SiS.3D.TexTurboMode=1 and SiS.3D.TexTurboMode=0. In case of SiS.3D.TexTurboMode=1, the level of detail increases, texture bi-linear filtering becomes normal and it appears possible to enable fully-fledged tri-linear filtering.
In case of SiS.3D.TexTurboMode=0, that is when no "turbotexturing" is enabled, the level of detail increases even greater and nearly reaches that of NVIDIA GeForce3 Ti200.
The screenshots below are taken from Serious Sam: The Second Encounter in all three modes: on the left you can see bi-linear filtering and on the right - tri-linear filtering enabled in the games settings:
| Bi-linear filtering | Tri-linear filtering | |
SiS.3D.TexTurboMode=3 | ||
 |  | |
SiS.3D.TexTurboMode=1 | ||
 |  | |
SiS.3D.TexTurboMode=0 | ||
 |  | |
Well, the filtering quality in case of SiS.3D.TexTurboMode=1 and SiS.3D.TexTurboMode=0 is incomparably higher than that provided by default.
For a better comparison, have a look at the same scene processed by NVIDIA GeForce3 Ti200. Again, you can see the results of bi-linear filtering on the left and tri-linear filtering on the right:
 |  | |
| SiS.3D.TexTurboMode=0 | SiS.3D.TexTurboMode=3 Multi-texturing disabled |
By the way, the remarkable thing is that with disabled multi-texturing even with SiS.3D.TexTurboMode=3 you can still enable tri-linear filtering. In "Turbo mode" without multi-texturing Xabre provides almost as good filtering quality as in case SiS.3D.TexTurboMode=0.
Two screenshots below are taken from Serious Sam: The Second Encounter. On the left the scene with SiS.3D.TexTurboMode=0 and on the right - SiS.3D.TexTurboMode=3 with disabled multi-texturing:
 |  | |
| Bi-linear filtering by NVIDIA GeForce3 Ti200 | Tri-linear filtering by NVIDIA GeForce3 Ti200 |
Well, the things with texture filtering quality provided by SiS Xabre have become more or less clear now. As for the performance in all these modes considered (it is not for nothing that the developers taught Xabre to do "turbo-texturing"), we will return to it later in a special section devoted to performance.
Xabre from SiS allows enabling Full-Scene Anti-Aliasing either via Xabre 3D Wizard or with SiS.3D.FSAA and SiS.3D.FSAAMode keys. If you set these keys equal to 1 and 0 respectively, Xabre will implement 2x supersampling mode, and to be more exact - 1x2. In case of these keys set to 1 and 1 correspondingly, Xabre works in FSAA 4x mode.
The screenshots below are taken from Serious Sam: The Second Encounter without FSAA, with FSAA 2x, and with FSAA 4x:
| No Anti-Aliasing | ||
 |  | |
2x Anti-Aliasing by SiS Xabre | ||
 |  | |
4x Anti-Aliasing by SiS Xabre | ||
 |  | |
SiS Xabre implements FSAA via supersampling, which you can clearly see from the screenshots on the right, where not only polygon borders appeared smoothed but also transparent textures.
As is known, enabling super-sampling results into clearer textures. Xabre is not an exception here: anti-aliasing improves textures quality in "turbo-mode" (you can see a screenshot without FSAA on the left and the one with FSAA 4x on the right):
 |  | |
| Speed mode: No FSAA | Speed mode: FSAA 4x |
… as well as in "quality" mode (again, no FSAA on the left, FSAA 4x on the right):
 |  | |
| Quality mode: No FSAA | Quality mode: FSAA 4x |
For a better comparison you can see the same scene processed by NVIDIA GeForce3 Ti200: enabling 4x multi-sampling doesn't tell on the textures quality:
 |  | |
| No FSAA by NVIDIA GeForce3 Ti200 | FSAA 4x by NVIDIA GeForce3 Ti200 |
Unfortunately, the implementation of Full-Scene Anti-Aliasing turns into dramatic performance drops. The results of the FSAA performance tests in Quake3 Arena are given below. No comments will follow this disaster:
However, hope is usually the last thing to die, so we still have some vague hope that with the new drivers the performance of Xabre based solutions with enabled FSSA will improve up to some acceptable level.
The correctness and quality of the pixel shaders implementation can be checked with the help of 3D Mark 2001 SE scenes. Remembering about the problems with the texturing quality provided by SiS Xabre, we resorted to SiS.3D.TexTurboMode=3 (it is used by default) and SiS.3D.TexTurboMode=0.
| SiS.3D.TexTurboMode=0 | SiS.3D.TexTurboMode=3 | |
 |  | |
SiS.3D.TexTurboMode=0 | SiS.3D.TexTurboMode=3 | |
 |  |
For a better comparison here is the same scene by NVIDIA GeForce3 Ti200:
 |  |
As you can see from the screenshots, enabling texture "turbo-mode" works only for textures laid ordinarily: have a look at the bridge stone-work. The quality of the lake surface where the pixel shaders are used doesn't change.
Nevertheless, the level of detail provided by SiS Xabre with Pixel Shaders involved appeared slightly lower here. As you may see, NVIDIA GeForce3 Ti200 creates a "wavier" lake surface:
| Pixel Shader by SiS Xabre | Pixel Shader by NVIDIA GeForce3 Ti200 | |
 |  | |
Advanced Pixel Shader by SiS Xabre | Advanced Pixel Shader by NVIDIA GeForce3 Ti200 | |
 |  |
The only comment here: the surfaces where SiS Xabre uses Pixel Shader look as if their level of detail were slightly lower.
| EMBBM by SiS Xabre | EMBM by NVIDIA GeForce3 Ti200 | |
 |  | |
Point Sprites by SiS Xabre | Point Sprites by NVIDIA GeForce3 Ti200 | |
 |  |
As for the quality of Point Sprites implementation by SiS Xabre, we have no complaints here. However, EMBM doesn't seem to be its trump at all. If you take a closer look at the screenshot generated by Xabre, you will be able to notice a lot of blocks 2x2 pixels all coloured with one colour. Is it another kind of SiS' own optimization? Well, quite possible…
So, now that we have answered all the question you might have about the image quality, it's high time we passed over to the performance analysis.
As usual, we would like to start with synthetic benchmarks, as it is much more important than games, you know ;)
Xabre T&L unit demonstrates beautiful performance, which is just a bit lower than that of ATI RADEON 8500.
In case of 8 light sources Xabre takes the lead. SiS' engineers did a great job: since the times of SiS 315 (see our review), when the latter was simply smashed to pieces by the competitor, GeForce2 MX200, the situation has changed drastically :)
Xabre doesn't have hardware support of Vertex Shaders, that is why we were not surprised to see that its result was almost equal to that shown by NVIDIA GeForce4 MX440, as the latter also has no Vertex Shaders unit.
As we have already found out the key responsible for the texturing quality doesn't tell on the pixel shader quality that is why these tests were carried out with the default SiS.3D.TexTurboMode=3:
The hardest tests for SiS Xabre appeared pixel shader performance tests. Of course, it is not shameful to be defeated by a match, but to let your rival turn 2-3 times faster is too much, really…
It is probably the absence of such architectural solutions as HyperZ by ATI and Lightspeed Memory Architecture by NVIDIA, which make the use of the available graphics memory bandwidth more efficient. The second possible reason of this failure might be the imperfect architecture of the Xabre's Pixel Shader unit, because Xabre appeared SiS' first experience in the field.
The fillrate test proves that Xabre doesn't work with the graphics memory so efficiently. This is absolutely evident: working at the same frequencies as ATI RADEON 8500 LE and at much higher frequencies than NVIDIA GeForce3 Ti200, Xabre gets beaten by both.
Only using compressed textures and "turbo-texturing" mode the graphics core managed to show its best and to nearly reach the theoretical maximum:
Now let's pass over to the gaming tests:
Xabre performed excellently in 800x600, however as the resolution grew up it had to step back under the onslaught of more powerful ATI RADEON 8500LE.
The performance drop caused by the disabled "turbo-texturing" appeared not so great as we had expected, and even with the highest quality settings Xabre remained ahead.
Here Xabre performed a bit worse than in car Chase, because there are more textures used and higher Overdraw rates.
In the Quality mode, that is when the image quality is as good as that by the competitors, Xabre falls behind even NVIDIA GeForce4 MX440, while with enabled "turbo-texturing" it managed to reach NVIDIA GeForce3 Ti200.
Here Xabre appeared between NVIDIA GeForce3 Ti200 and GeForce4 MX440 when tested with default settings. However, as soon as we disable "turbo-texturing" it rolls back to the very last position. Luckily, in the intermediate quality mode, Xabre doesn't lose much of the speed.
Nature test uses Pixel Shaders. As we have already seen above, Xabre works with them very slowly. So, no wonder the performance of our hero is not that impressive here.
Despite the beautiful scenes created by the Siege Engine in Dungeon Siege, the textures are not that big and hardly use any multi-texturing. Therefore, Xabre's "turbo-texturing" provides almost no advantage. Here Xabre turned an outsider.
The results of Xabre based cards depend a lot on the texture filtering mode. But in general, Xabre performed very well.
In Quake3 Arena, unlike Dungeon Siege, Xabre had to pay a huge price for the improvement in the texturing quality. Don't be surprised, the results in Quake3 Arena have always been dependent almost only on the texturing speed and graphics memory bandwidth.
Well, I would like to sum up the results of the performance tests and to draw some preliminary conclusions. Having run all the tests and real games we got a very clear idea of "turbo-texturing" and its importance for Xabre family.
Compared with the competitors, Xabre cannot boast very efficient work with the graphics memory. It is most likely to be a not enough "polished" cache structure or their insufficient size. Also please bear in mind that Xabre doesn't have such efficient technologies improving the work with graphics memory as LightSpeed Memory Architecture / LMA II of NVIDIA GeForce3 / GeForce4 MX or HyperZ II of ATI RADEON 8500. Early Z-test presumably implemented in Xabre, which allows the chip to avoid texturing invisible pixels, doesn't seem to be able to save the situation.
In order to make its Xabre baby look nice against the background of more powerful competitors, SiS decided to take another way: they replaced bi-linear texture filtering with approximation, tried to save on selecting additional texture samples, etc. By the way, Xabre can involve its "turbo-mode" not only for speeding up the work with textures, but also for lighting calculations (SiS.3D.LightTurboMode key, disabled by default), for alpha-blending implementation (SiS.3D.AlphaBlendTurboMode key, disabled by default), and for the whole bunch of other functions, I'm sure.
There is nothing bad about these "turbo-modes", actually. If the chip can do something sacrificing image quality for the sake of success, it is excellent, because there will always be users who do not care about clear-cut shapes and correct lighting, but hunt only for performance. On the other hand, I belong to those who prefer beautiful picture to high fps rates.
The conclusion will be as follows: let the users adjust these parameters according to their own needs and everybody will be happy. I hope SiS guys will implement this option in the next driver versions.
Although I am really longing to do it, I will refrain from drawing final conclusions now about the popularity or non-popularity of the new SiS baby.
The chip appeared pretty fast and the cards based on it are most likely to be not very expensive. Pixel Shader support gives Xabre a couple of trumps in the battle with the low-cost competitors from other graphics chip developers. We would also like to stress as one of the indisputable highs SiS' changed attitude towards their products. The drivers have become much more mature and will hopefully grow up to those from NVIDIA and ATI soon. There are almost no artifacts in games that do not fall under any reasonable explanations, and the image quality can be improved within 10 seconds with a couple of simple tricks. The overall picture could be very optimistic for SiS Xabre if…
…if we were sure that the prices of Xabre based graphics cards will be adequate to their performance (with disabled "turbo-modes", of course :) and their functionality. The Value graphics cards market is really packed with the whole lot of products now, and it will be even more packed as soon as ATI RV250 comes out, which will push ATI RADEON 8500/8500 LE into the value sector once and for all. As we have already seen, it is very hard for Xabre to compete with monsters like that, so there will be only one way: to reduce the prices. And how much should a card based on SiS Xabre 400 cost, so that it could attract your attention compared with GeForce3 Ti200 or RADEON 8500/8500LE? I think you can imagine now :)
On the other hand, Xabre competes with the fastest NVIDIA GeForce4 MX, older GeForce2 Pro/Ti and ATI RADEON 7500, which do not support Pixel Shaders. They will also get cheaper and cheaper, that is why Xabre may face some new surprises here as well: its price will have to be attractive against the background of these cards, too.
All in all, what we are looking forward to now, is the finalized drivers (which need a little bit of polishing) and the most important thing: the Xabre pricing info.
Elitegroup, which is well-known as a manufacturer of low-cost solutions of good quality has huge production capacities at its disposal that is why it will do Xabre only good that this company paid special attention to it. ECS AGP400 graphics card based on SiS Xabre 400 made favourable impression having proven reliable and stable throughout the tests. We suppose that the price of ECS AG400 will also be very attractive.
So, let's sum up:
Highs:
Lows: