My 2008 Mac Pro has been replaced for daily work by a Mac mini. But I still play windows games on the Mac Pro. In fact it only has one hard drive in it, that has Win 7 on it. The card in it now is a Radeon HD4870 series, and is showing its age. Can I just put a GTX970 or similar in it?, assuming the power connections can be sorted. I'd love to give it a new lease of life, than spend a ton of cash on building a new windows gaming machine. Can it be done?