I recently upgraded my iRacing rig to a ATI HD6870 GPU and a 900W power supply and I can now drive triple monitors at 1920x1080 resolution. I was at 3x1280x1024 before. But, I was disappointed with the frame rate of around 35fps worst case at Road America. I'd read I should be getting 70. After some research I'm pretty sure the problem is my CPU. I have an AMD Athlon x4 620 which is a quad core 2.6Ghz chip with no L3 cache. I tried overclocking it to 3.2Ghz last night and the frame rate rises to around 43fps.
It looks like an Intel i5/i7 setup is best for iRacing at this resolution. Road Racing on triple screens uses a lot of CPU and Intel chips are simply faster. If you want the best frame rates, buy Intel for now. That said, I'm not about to buy a new motherboard, RAM and processor. So, I bought a new processor. An AMD Phenom x4 BE 970. This is a quad core chip at 3.5Ghz with 6MB L3 cache. It just drops in to my ASUS M4A785G motherboard and I like that about AMD a lot.
My Nvidia GT240/Matrox Triplehead2go/AMD 620 rig was plenty fast frame wise BTW if you're happy at 3x1280x1024.
I bought it at newegg for 190. The AMD 6 core chip is 230 but only clocks at 3.2Ghz so I figured i'm better off with faster cores and fewer of them since iRacing only uses 2 cores right now, maybe 3 cores in an upcoming release according to rumors.
The chip should arrive this week and I'll post the numbers.
