Here is the situation. When I boot into Windows, my PCIe bus is changed from x16 to x1. When I reboot and load Mac OS again, it is still x1. When I reboot again and go back in to Mac OS, it is finally back to x16. I have tested this with WinXP, Vista, and Windows 7. I have tested this with the Apple drivers from the Leopard DVD, Snow Leopard DVD and the latest drivers from nVidia. At first I thought it was because I was loading games and stressing the GPU. Then I noticed it did the same thing without running any 3D games at all. Next I thought it was a temperature issue. So I installed SMC fan control and revved the fans up to max speed and rebooted in to Windows. The fan settings stuck as expected. I rebooted into Mac OS and the PCIe bus was again set to x1. I am at a loss. My best guess is that this is a firmware bug of some sort. I highly doubt it is because of the OS or driver version due to all of the combinations I have tried. Any ideas? Also, if it is hardware or firmware based, will Apple even do anything about it? Windows still "works" but just with a very slow GPU. Curious to see what you all think.