ATI shows off PhysX architecture

ATI chose Computex to show off its PhysX architecture which can use a third PCI-Express slot to speed up PC graphics.

Prototype drivers allow a modest ATI card - a 1300 or better - to act as a physics processor in conjunction with either a second ATI card, or two ATI cards working in parallel using the company's Crossfire technology. The system supports the Havok FX physics engine.

It will launch as an Intel/ ATI combination, followed by a version supporting AMD processors. Games that use it are at least six months away.

In press briefings, ATI showed off numbers where a lowly RV530 beat an Nvidia G70 and G71.

ATI claimed that when using PhysX, the RV530 was four times faster than G70 card, a number that rises to 15 times when comparing a R580 to a G70 series card.

ATI also claimed the X1600XT is two times faster, and the X1900XTX is nine times faster, than Ageia's dedicated physics processor.

But these figures were provided by ATI, and were not independently verified.
As no games run across Havok and PhysX right now, any numbers appear to be theoretical.

Where ATI does have a clear lead over Nvidia is the asymmetry. You can plug in anything from an X1600 series GPU up, and you can mix and match.

X1300 CPUs will work, but by the time the games come out, X1600 will be the base card.

ATI said the performance was down to the branch prediction hardware. If an instruction stream has a branch, ATI can process it with no overhead.

Nvidia’s 'green' architecture, as ATI calls it, is shown to have a six clock overhead. Any instruction has its latency plus six, leading to a lot slower execution.

Provided it works and does not suffer delays similar to those seen with Crossfire, it gives ATI a credible alternative Nvidia.

A versiobn of this article first appeared on the Inquirer

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