I just upgraded to Yosemite yesterday on a 4,1 Mac Pro which also has a GTX 570 and GT 120 in it. Its been working fine except I've gotten a couple kernel panics in a few situations. Waking up from sleep, after a few seconds if I try to do something in an app, say "Open" a file from Photoshop, the screens lock up, go black / blue / or are just static screen noise. I have several "SystemUIServer wakeup_resource.diag" from each crash but nothing that looks like a kernel panic log I'm used to. It's also crashed twice playing a video in Quicktime, and in Quickview Preview, both of which I think are using core video? Because VLC seems to play these fine. I've seen this from an old thread: http://forums.macrumors.com/showthread.php?t=1583723&highlight=gtx+570+gt+120 That seems to suggest issues with the 570/120 but I've run this combo successfully for years in Mavericks/Lion. Trying to figure out if anyone else has experienced similar issues? Contemplating downgrading to Mavericks? Or maybe a 970 if its a dual card issue?