Hi Gang, Mac Pro 2008 (early, 8 core) OSX 10.8.3 EVGA 660 Ti GT 120 Had been running with my new 660 for months with no problem other than the sleep issue then one day my fans started revving out of control. Several reboots later, nothing. PRAM etc, nothing. Check wiring for loose connections etc. Was concerned it was a faulty sensor but decided to swap the GT120 back in trying desperately to isolate the problem. Well in the end it was a SMC reset that seemed to do the trick and was running fine beyond that for a couple weeks (with the GT120). Wanting to put the 660 back in, I was met with huge problems and nothing more than black screens. Tried all sorts of combinations, new Nvidia driver and pref panel, different slots, etc. Never really got it working other than one time. I was so happy and was putting the side cover back on when all of a sudden a fan revved hard for 3 seconds (not sure which fan, card's or mac's) and boom, black screen again. Anyhow back to GT120 again and all is working smoothly. Bummed out thinking the new card is failing. But can't give up on it yet. Any help or suggestions would be helpful.