Hey all, this is my first post here and I have searched for my problem but not found anything. I installed an EVGA 770 GTX 4GB Classified in my 2009 Mac Pro (hacked to 5,1) and unfortunately it just clicks and nothing happens. I tried every combination of 6 pin to 8 pin adapter I could think of. I put my old GT120 back in to see that everything ran and it did. So the PSU isn't shot or anything. But as soon as I install the 770 back in, it just clicks and does nothing. It is a non-Mac rom PC version. But it should still work shouldn't it? Could my mini 6 pin power cables be defective? I am about to pop the card into a PC this week to make sure the card actually works (got it open box from EBay). But I was hoping someone had a similar experience to mine and could help me out. Could the Classified OC internal clock be too much for my Mac? Do I need to send it to MacVidCard so they can modify the clock speed to have a lower power draw? Any help would be awesome.