Pixel filling power
All of the clock speed and pixel pipeline numbers that ATI is juggling to achieve its ideal product mix also determine overall performance. Here's a look at the highlights of how the new cards compare to the most common competition.

  Core clock (MHz) Pixel pipelines Peak fill rate (Mpixels/s)Texture units per pixel pipeline Peak fill rate (Mtexels/s) Memory clock (MHz) Memory bus width (bits) Peak memory bandwidth (GB/s)
GeForce 62003004120011200TBD128TBD
Radeon X30032541300113004001286.4
Radeon X600 Pro40041600116006001289.6
GeForce FX 5700 Ultra475419001190090012814.4
Radeon 9600 XT50042000120006001289.6
Radeon X600 XT500420001200074012811.8
GeForce 66003008*240012400TBD128TBD
Radeon 9800 Pro380830401304068025621.8
Radeon 9800 Pro 256MB380830401304070025622.4
GeForce FX 5900 XT400416002320070025622.4
Radeon X70040083200132006001289.6
Radeon 9800 XT412832961329673025623.4
Radeon X700 Pro420833601336086412813.8
Radeon X700 XT4758380013800105012816.8
GeForce 6800 3251239001390070025622.4
GeForce 6600 GT AGP5008*20001400090012814.4
GeForce 6600 GT5008*200014000100012816.0
Radeon X8004001248001480070025622.4
GeForce 6800 GT35016560015600100025632.0
Radeon X800 Pro4751257001570090025628.8
Radeon X800 XL40016640016400100025632.0
GeForce 6800 Ultra42516680016800110025635.2
Radeon X800 XT50016800018000100025632.0
Radeon X800 XT Platinum Edition52016832018320112025635.8
Radeon X850 XT52016832018320112025635.8
Radeon X850 XT Platinum Edition54016864018640118025637.8

ATI maintains its lead in clock speeds and theoretical peak performance over NVIDIA at the very high end, at least in terms of single cards. The X850 XT Platinum Edition gains a little bit of speed over the previous Platinum Edition card, but NVIDIA has also picked up 25MHz on the core speed of its GeForce 6800 Ultra. Not all 6800 Ultra cards run at 425MHz—most run at 400MHz—but Asus and BFG Tech are selling 425MHz cards, and the cards we tested for this review had a 425MHz core clock speed.

Here's how those theoretical numbers work out in a synthetic fill rate test.

Few of these cards achieve anything like their peak theoretical fill rates when applying only one texture per pixel, but they do much better with multitexturing. Note that the Radeon X850 XT is just a tad slower than the X800 Platinum Edition, despite the fact that they share the same core and memory clock speeds. The R480 chip may be a little bit slower clock for clock, or it may have more relaxed memory timings. Whatever the case, it's only a minor difference.