Late 2009 2.26ghz 8-core with 6 gig RAM and Apple 4870. Windows 7 is installed under Boot Camp 3.1. I basically only use it to play COD4 and one or two other FPS games. Last evening playing COD4 for the first time on this machine, the whole computer shut down unexpectedly. It automatically rebooted into OSX, and after it loaded I noted that Temp Monitor showed the CPU temp at 55C. It was decreasing rapidly down to my normal operating temp of about 38C. I suspect overheating, probably CPU's since video card performance was normal up until shutdown. I'm not sure of the solution, but I'm prepared to switch back to XP if necessary, or increase fan speeds. Any observations? How would I increase fan speed on a Mac Pro 4,1 under Windows 7?