Thanks Hercules for this very interesting article, read on!
John Carmack is the first to confirm a hardware bug with Radeon 8500 cards, this is ore commonly known as the "Poly" bug withing the ranks of radeon 8500 owners. Basically frame rates drop to near slide show speeds for NO apparent reason. Here is what he had to say:
A high polygon count scene that was more representative of real game graphics under heavy load gave a surprising result. I was expecting ATI to clobber Nvidia here due to the much lower triangle count and MUCH lower state change functional overhead from the single pass interaction rendering, but they came out slower. ATI has identified an issue that is likely causing the unexpected performance, but it may not be something that can be worked around on current hardware.
I can set up scenes and parameters where either card can win, but I think that current Nvidia cards are still a somewhat safer bet for consistent performance and quality.
On the topic of current Nvidia cards:
Do not buy a GeForce4-MX for Doom.
Nvidia has really made a mess of the naming conventions here. I always thought it was bad enough that GF2 was just a speed bumped GF1, while GF3 had significant architectural improvements over GF2. I expected GF4 to be the speed bumped GF3, but calling the NV17 GF4-MX really sucks.
GF4-MX will still run Doom properly, but it will be using the NV10 codepath with only two texture units and no vertex shaders. A GF3 or 8500 will be much better performers. The GF4-MX may still be the card of choice for many people depending on pricing, especially considering that many games won't use four textures and vertex programs, but damn, I wish they had named it something else.
News source: Shacknews