Xabre 400 Roundup - August 2002
By: Mikhail Dagterev
Introduction
Keeping our eyes fixed on the video cards industry, we notice the stars of the first magnitude mostly, thus producing the impression of a specific graphics chip manufacturerin the consumer mindset. Mind you, nobody would argue that GeForce4 Ti4600 as well as Radeon8500 are nVidia ATi top performers. These names have firmly fixed in the gamer's mindset as a standard of speed, reliability, trouble-free piece of hardware. But, partitioning the video cards market into the nVidia andATI domains we are sometines unaware of other video cards manufacturers, not so bright but no less ambitious than the two industry giants. Trident and SiS are definitely not able to withstand competition against nVidia and ATi in terms of high-performance high-end video cards, so they target at the market of lower-end video cards which are supplied as OEM components to equip new office computers or sold to those on a tight budget, who don't care much about gaming speed/performance. Where "price-performance ratio" is the key factor, any company with a fair amount of video cards manufacturing experience might easily press the competitors, ATI and nVidia, and win a niche. But how deep that niche could be depends much on the product which represents the company's image.
Traditionally, video cards based on SiS chipsets have gained little credit. Even though SiS missed an opportunity to switch to the 2D/3D accelerators having a strong 3D bias, the company is determined to retake positions and won't step back. If SiS 305 chip could hardly be a match for competitors in none of the parameters, SiS 315 in the end proved on par with low-end nVidia GeForce2 MX200 video cards. If video cards manufacturers hadn't overlooked SiS315 at the right time, it wouldn't have passed unnoticed. Today SiS is manufacturing a new line of video chips under the new name - Xabre. SiS is determined to promote Xabre chips in all the three groups of the video cards market - Value, Mainstream and Performance.
First, SiS Xabre400 video chips of the performance class will be released, then SiS will announce a slower "mainstream" Xabre200 video card and Xabre80 as GPUs for the low-end video cards. There are also plans to launch Xabre600 (overclocked version of Xabre400 and Xabre II, a brand new graphics chip). The main competitors for Xabre400 are GeForce4 MX440/460, GeForce3, GeForce4 Ti4200 and Radeon 8500LE. Let's take a look at how Xabre-family GPUs rank among the rivals.
| Graphics Chip |
NVIDIA GeForce4 Ti4200 |
NVIDIA GeForce4 MX460 |
ATI Radeon 8500 |
ATI Radeon 9000 Pro |
SiS Xabre400 |
| Chip technology |
256 bit |
256 bit |
256 bit |
256 bit |
256 bit |
| Process technology |
0.15 mk |
0.15 mk |
0.15 mk |
0.15 mk |
0.15 mk |
| Q-ty of transistors |
63 mln |
- |
60 mln |
- |
- |
| Memory bus |
128 bit DDR |
128 bit DDR |
128 bit DDR |
128 bit DDR |
128 bit DDR |
| Core speed, MHz |
250 |
300 |
275 |
275 |
250 |
| Memory speed, MHz |
514 MHz - 64MB
444 MHz - 128 Mb |
550 |
550 |
550 |
500 |
| Max. memory capacity |
128 Mb |
128 Mb |
128 Mb |
128 Mb |
128 Mb |
| Memory bus bandwidth, GB/s |
8. 2 |
8. 8 |
8. 8 |
8. 8 |
8. 0 |
| AGP bus |
1x/2x/4x |
1x/2x/4x |
1x/2x/4x |
1x/2x/4x/8x |
1x/2x/4x/8x |
| Memory type |
SD/BGA 3.3-4 ns |
BGA 3.3 ns |
SD/BGA 3.3 ns |
SD 3.3 ns |
SD 3.3-4 ns |
| Pixel pipelines |
4 |
2 |
4 |
4 |
4 |
| Texture blocks per pipeline |
2 |
2 |
2 |
1 |
2 |
| Textures per cycle |
4 |
4 |
3 |
6 |
4 |
| Fillrate |
1000 MPixels/sec
2000 MTexels/sec |
600 MPixels/sec
1200 MTexels/sec |
1100 MPixels/sec
2200 MTexels/sec |
1100 MPixels/sec
1100 MTexels/sec |
1000 MPixels/sec
2000 MTexels/sec |
| DirectX |
8.1 |
8 |
8.1 |
8.1 |
8.1 |
| RAMDAC |
Two, 350 MHz each |
Two, 350 MHz each |
Two, 400 MHz each |
Two, 400 MHz each |
One - 400 Mhz, external - 135 MHz |
| Antialiasing methods |
Multisampling |
Multisampling |
Supersampling |
Supersampling |
Supersampling,
Jitter |
| Memory optimization |
LMA II |
LMA II |
Hyper Z II |
Hyper Z II |
N/A |
| Display outputs |
2 |
2 |
2 |
2 |
2 |
| Bits per color channel |
8 |
8 |
8 |
8 |
8 |
|
GPU |
| T&L Support |
Yes, SuperScalar T&L |
Yes, SuperScalar T&L |
Yes |
Yes |
Yes |
| Vertex shader blocks |
2 |
NO |
2 |
2 |
NO |
| Vertex shader version |
1.1 |
1.0 |
1.1 |
1.1 |
1.1 |
| Pixel shader version |
1.3 |
NO |
1.4 |
1.4 |
1.3 |
| Textures |
| Cubical environment maps |
Yes |
Yes |
Yes |
Yes |
Yes |
| Anisotropic Filtering Level |
8 |
8 |
8 |
8 |
N/A |
| 3D textures |
Yes |
NO |
Yes |
Yes |
Yes |
| Env. Mapping (EMBM) |
Yes |
NO |
Yes |
Yes |
Yes |
| Extras |
- |
MPEG2 decoder |
- |
MPEG2 decoder |
3D glasses output |
In theory, Xabre400 is quite powerful and even superior in some ways to the competitors. This chip lacks many flaws typical of the GeForce4 MX line. For example, pixel shaders and Environmental Mapped Bump Mapping are supported, and even though Xabre as well as GeForce4 MX have no hardware support for vertex shaders, they can be emulated with the CPU resources. More than that, Xabre is the first chip to support AGP 8x which is gradually taking over. Frankly, the speed difference between AGP4x and AGP8x is virtually not seen to the naked eye, and today very few applications can take advantage of that new standard. Moreover, on VIA motherboards Xabrecan run at AGP2x only, so it's still yet to be seen which is better - an AGP8x with a dubious AGP4x support or a true AGP4x on any motherboard?
| AGP Comparisons |
|
AGP |
Bus speed |
Voltage |
Bandwidth |
Note |
| 1x |
66 MHz |
3,3 V |
266 GB/s |
1 bit passed per cycle |
| 2x |
66 MHz |
1,5 / 3,3 V |
533 GB/s |
2 bits passed per cycle |
| 4x |
66 MHz |
1.5 V |
1 GB/s |
4 bits passed per cycle |
| 8x |
66 MHz |
0.8 / 1.5 V |
2.1 GB/s |
8 bits passed per cycle |
It's interesting that from SiS315 this Xabre inherited a joint operation with SiS301 chip responsible for TV-out or output to a second monitor. This chip has a very weak RAMDAC whose frequency is merely 135 MHz, which was acceptable in the GeForce2 MX times but is not justified today when RAMDAC of 350 MHz or higher frequencies is integrated into graphics chips. On the other hand, use of diverse SiS301 brands allows to produce video cards with a DVI-interface, 3D-glasses output or TV-in socket. We'll compare various Xabre400-based video cards afterwards, but now let's look into thechip itself.
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