I feel like I already know the answer to this, but I've seen all sorts of Apple documentation to the contrary, so I'm a little sketched out and wanting assurance, but does the NVIDIA GeForce GT 120 that was the stock part of the Mac Pro (Early 2009/4,1) work just fine in the Mac Pro (Early 2008/3,1)? I'm considering recommending such a card for a friend with an Early 2008/3,1 Mac Pro who is stuck with the Radeon HD 2600 XT. And I feel like even though the GT 120 is also a weaksauce card, it's not failure-prone and it is at least a little better (with double the VRAM of the former and OpenCL support). But I don't want to propose that I can be assured that it won't break either the card or the Mac Pro.