AMDZone has updated their Quake 4 1.05 beta benchmarks with a fix from Nvidia to get dual core support to work properly.
We discussed our results with AMD and Nvidia and they began investigating as we continued our tests. A couple of days went by and our results remained the same. Then Nvidia got back to us about discovering that there was indeed a problem with their 80 series drivers from 81.84 and beyond. They believe their dual core optimizations in those drivers could be interfering with the new dual core support in Quake 4. They provided us with registry keys to add to disable dual core support in their drivers. Armed with this new information we benchmarked again. We tested again with the same hardware setup as the previous tests, and this time all testing was done manually using r_usesmp 0 and 1 to change the SMP mode on and off.. Read on over here.