Technology wise, we have already covered the X800 XT in some detail, and fundamentally the X850 XT PE offers the same feature set.
The X850 XT PE uses the same 130nm process of the 9600XT, if you look back to our 9800 reviews, you will see that they ran with a larger 150nm process. The HIS IceQ II X850XT PE runs at the same speed as the ATi retail variant, with 540MHz for the core and 590MHz for the memory. This makes it slightly faster clocked than the X800 XT PE variant (20MHz faster on the core and 30MHz faster on the memory). The X850XT iTurbo runs at a default clock speed of 520MHz, the same as the X800XT PE, but memory is a little less at 540MHz. As with all X850 XT cards, the IceQ II cards have 16 pixel pipelines. This is four more than the X800 Pro and a whopping 8 more than the old 9800XT.
ATi have chosen not to implement Shader Model 3.0 with their R420 graphics processor, a feature that the 6800 does support. Whilst no new visual effects become available with SM3, it does allow instructions to be executed more quickly, and thus you can code for more detail when a SM3 architecture is detected. R420 increases the number of vertex shaders from 4 to 6, which coupled with increased clock speeds increases the vertex performance over the 9800XT by nearly 100%. The vertex shader remains largely unchanged from R300, although it does have enhancements in SIN and COS instructions allowing these to be executed in a single clock cycle.
Hyper-Z functions are present and correct, being carried over from the prior generation. They work on a per quad basis (each pipeline holds a separate hyper-z section) meaning that the Hierarchical Z-buffer is scalable to the number of pipelines, whether the card is a 16x1, 12x1, 8x1 or even a 4x1 configuration.
3Dc is an exciting new compression technology designed to bring out fine details in games while minimizing memory usage. It is the first compression technique optimized to work with normal maps, which allow fine per-pixel control over how light reflects from a textured surface. With up to 4:1 compression possible, this means game designers can now include up to 4x the detail without changing the amount of graphics memory required and without impacting performance.
