Hey guys, i tried posting on here recently, but only received one reply. I Bought a GTX 660 ti recently after reading how well it works with the newest OSX Yosemite. I used the card for about a week or two running amazing on my 2009 Mac pro 4,1. I wake my computer after it was on all night, like usual and i have NO signal coming out of the video card. Everything is running fine, the fans smooth and when i put in the Original Nvidia Card to test if the machine was okay everything worked fine. I put in the Nvidia card with the other card together, and Sys Info reads the card and nothing seems out of the normal it was just working fine, didn't take it out since i purchased the card! Anyone know if i should reinstall Yosemite? I also tried installing the newest Nvidia card drivers and still no luck ):