So I've been going through hell all day trying to install this fresh Windows 8 System Builder DVD on a Mac Pro early 2008. I should note a few things about my machine. My original optical drive recently kicked the bucket so I picked up a new sata drive and attached it to one of the extra two portals. I also replaced my original graphics card with the geforce gt 120 hooked up to a mini displayport cinema display. I also have an ssd as my primary drive. I'm running the latest mountain lion with all of the updates. I reset my SMC/PRAM and even in a silly attempt reinstalled mountain lion from scratch. I started with the bootcamp assistant, setup a new partition, reboot and it goes to a grey screen and freezes. Nothing. I reboot and hold alt and see two dvd boot options, one "Windows" and one "EFI Boot". I select "Windows" and it immediately freezes. I reboot and select "EFI Boot" and it goes to a grey screen, then the apple logo forever, then strangely boots up to osx as normal. Knowing the potential problems with the optical drives on the extra two sata ports, I rip the dvd to an iso using imgburn in my vm as I couldn't get a good iso out of disk utility. I modified bootcamp to enable the install a bootable usb which worked fine, but when I reboot, it freezes on the grey screen and goes nowhere. I reboot and hold alt for the bootscreen and it freezes as soon as I click the usb drive which also shows up as "efi boot" In a desperate attempt I made a small partition on my ssd and copied the install files over. Strangely it showed up in the boot list also as "efi boot" and when I selected it, it was a good old freeze just like the usb and dvd. I'm really at a loss here. I also installed rEFIT but in what seems like a dark twist of humor my bluetooth keyboard doesn't work, so I'm not sure if there's any promise there. I strangely noticed that the dvd boot option didn't show up in rEFIT but the USB seemed to show up. I'm going to try to pick up a keyboard in the morning. I also had the same problems with windows 7 so I know it's not a windows 8 thing. My only other thought is maybe it's something with my video card? As you can imagine, any suggestions would be immensely appreciated! Thanks.