![[H]ardOCP](/images/blank.gif){kind=small}
- Date:
- Monday , January 06, 2003
- Author:
- Brent Justice
- Editor:
- Sean Quinn
- Google +1
SiS Xabre 600 Review
Announced last November, the Xabre 600, successor to the Xabre 400, is poised to compete in the mainstream market, offering full DirectX 8.1 support. We examine the performance and "image quality" of this latest GPU from SiS.
Introduction:
SiS is well known for their integrated graphics chips, which end up being a cheap integrated solution for business users. What they have really lacked is a true gamer’s graphic chipset. They tried to get in on that territory back in June 2002 with the introduction of the Xabre 400. At the time they succeeded somewhat, with the Xabre 400’s feature support and performance winning out slightly against its competitor at the time, the GeForce4 MX. However, that did not last long. Two major problems plagued its existence. Both 3D image quality and drivers were not very good, showing very bad texture and filtering quality. More importantly was the fact that the Radeon 9000 Pro was announced in July and outclassed it both in performance and image quality. Falling prices on the GeForce4 Ti 4200 and Radeon 8500LE also pushed out the GeForce4 MX as well as the SiS Xabre 400.
SiS has gotten slightly behind, however, are still loosely following their original product roadmap. The Xabre 400 was released on time in Q2’02 but the Xabre 600 was originally supposed to be released in Q3’02 in the performance market, with their next generation chip, the Xabre II, being released in Q4’02. The Xabre 600 was officially announced on the 26th of November, 2002 which is a whole quarter behind schedule. It now looks as if the Xabre II will not be released until sometime in the first half of 2003.
Below you will first see their original roadmap and right next to it their brand new Xabre GPU Roadmap.
Their new roadmap shows the Xabre 600 being their last DX8 GPU in the performance market as well as their first .13 micron process GPU released in the second half of 2002. The Xabre II will continue on at .13 with full DX9 support in the enthusiast market sometime in the first half of 2003.
Hardware:
So what exactly is the Xabre 600 and what makes it better compared to the Xabre 400? SiS has thrown in a lot of marketing terms to explain these new features. "Duo300" is the first one we come upon, which simply refers to the fact that the core and memory speed are both clocked at 300MHz, referring to it as the “Duo300 function.” "Pro8x8" is next, relating to the AGP 8X and DirectX 8 support of this GPU. After that is the "Pixelizer", meaning that it supports DirectX 8.1 Pixel Shader version 1.3. There's also the "Vertexilizer Engine", which refers to the unique method SiS chose to use for the vertex shaders. We will talk about that in more detail a little later. We also cannot forget "Frictionless Memory Control", "Jitter-Free Anti-Aliasing", "MotionFixing Video Processor", and "Double Scene Technology". Also included with the Xabre 600 are the new "Xminator-II" unified drivers providing "XmartDrive", "XmartVision", and "XmartAGP".
Well, those all sound fine and dandy, but what the hell does it all mean? SiS has basically assigned a trademarked term to every feature they could think of on this card. We are going to put all of the terms aside and just examine this card on the hardware level and leave the marketing pitch behind.
The Xabre 600 GPU is designed on the .13 micron process, allowing it to run cooler and be clocked higher than the Xabre 400. The core and memory both run at 300MHz, which is up from the Xabre 400’s clock of 250MHz/250MHz. The package size for the core is 37.5 x 37.5 mm2, which is the same as the Xabre 400. It has 4 pixel pipelines with 2 texture mapping units per pipe. One very useful feature that you will see in the architecture layout above is the inclusion of Hardware Monitoring for this card.
The most interesting aspect of this card is the Vertexilizer Engine. In order to keep both costs and die size down, they did not go with a full hardware vertex shader engine in the GPU. In the very simplistic diagrams above, you can see that the traditional vertex shader engine is larger than the Xabre 600’s vertex shader engine. SiS felt that the CPU here may actually be able to perform vertex shader instructions faster than the GPU itself. I will quote from their whitepaper.
“When comparing the computing power of CPU and a GPU with hardware vertex shader. It is found that one of the most powerful processor with four parallel vertex pipelines can process 1.2G instruction per second, while a 2.5GHz CPU with SSE2 can process 10G instructions per second. The CPU is clearly more powerful than the most advanced graphics processor on the market. It was considered not optimal to have pure software vertex shader and pure hardware is just simply not cost efficient. This means that an optimized architecture might be the best alternative in a high-speed CPU age and at the same time would provide a good price to performance ratio.”
Xabre’s solution is what they call a Hardware Optimized Vertexilizer Engine.
“In order to improve performance and reduce the hardware design cost for vertex shader. The Xabre series GPU has implemented the so-called “HW Optimized Vertexlizer”. The hardware optimized architecture is as shown in figure 2. It is called “Hardware Optimized” because the GPU will process most of the runtime instructions; except and only for some minor operations which were much more efficient by the CPU. The driver can compile the vertex shader program in run time and flexibly uses the hardware accelerator. It supports Intel SSE/SSE2 and AMD 3Dnow! Instructions with full 32-bits floating point precision. The performance of vertex shader scales with CPU speed, the performance of the Hardware Optimized Vertexlizer would be benefited by upgrading the CPU. Other than the performance advantage, the smart vertices data movement will significantly save system memory bandwidth. Finally, the good news is that the vertexlizer engine can be upgraded without any hardware replacement.”
There are two very important features of their Vertexilizer Engine that are worth noting here. The fact is that this Xabre 600 should scale very nicely. As the CPU increases in speed, so will the performance of the Xabre GPU. The most interesting part is the fact that the vertex shader structure from the Xabre can be upgraded to future versions without any hardware replacement. This helps to ensure future compatibility with vertex shader 2.0 and above.
Here is a quick rundown of the other features supported:
Frictionless Memory Control – A highly specialized method for prioritizing blocks of data and controlling their movement, ensuring high priority information is bumped up to the front of the queue.
Jitter Free Anti-Aliasing – Supports 2x, 3x, and 4x supersampling.
MotionFixing Video Processor – Supports de-interlacing and motion compensation MPEG 2/1 decoding.
XMartDrive – This is basically automatic clock throttling, so that when you are not playing a game the card runs at a lower clock speed to reduce heat and power, and then when you start a 3D game it kicks it back up to regular speeds.
XMartVision – This is automatic gamma correction for changing the brightness if a game is too dark.
XMartAGP – This is basically its auto detection of whether it is in an AGP 2X/4X or 8X slot.
If you would like to read more about the Xabre 600’s hardware features, you can browse on over to www.xabre.com where you will find information such as an overview of the specs, a complete feature list, and even a quick presentation.
The Card:
The attribute you will most likely notice is the striking black PCB against the gold colored HSF unit. This already leans towards the crowd that likes a little show when touting their systems. There are about three different jumper blocks on this card to enable or disable various things such as NTSC or PAL mode. Other than that, the layout is a pretty simple design.
It has a VGA port, a DVI port, and a TV-out port which all seem to be pretty standard fare nowadays. This card does support dual monitors if you hook up a DVI-VGA adapter. The RAM included on our card is Hynix HY5DU283222 F-28, which according to their PDF is rated at 2.8ns (350MHz). This conflicts with the Xabre 600 presentation, which says the Xabre 600 uses 3.3ns RAM. It seems our card has faster RAM on it than SiS says will ship with retail cards, which will run at 300MHz memory speed (our card came clocked stock at 315MHz memory speed).
After taking the HSF unit off, I found that a sufficient amount of thermal paste had been applied, but the footprint showed that the heatsink itself was not being held tightly against the GPU. It came off quite easily, revealing the core itself.