I tripped over a rather annoying issue with upgrading to 10.10.2 on a machine with a 980 in it.
It is a mac pro, and I run the Nvidia web drivers (since in theory, the 980 isn't a "supported" card, but it "just works"). Well, 10.10.2 renders the prior version of Nvidia's drivers unusable, but this wasn't a problem on the 680 boxes, which run fine on Apple's drivers. The 980 also ran fine on Apple's drivers in 10.10.1.
Apparently, in Apple's never-ending quest to render useless that which wasn't soldered in in the factory, 10.10.2 provides no such luxury. The update installed, and the machine rebooted, and then went dark. Which isn't unusual, since the 980 doesn't have mac-compatible firmware, you don't get the initial boot screens, you just wait for the login screen. In thiscase never came.
In goes the gt 120, so I can get a boot screen, and the bloody thing is booting, crashing, lather, rinse repeat.
To cut an otherwise and already terribly long-winded story short, I actually had to pull out the 980, boot on the 120, install the new nvidia drivers for 10.10.2 (which won't install if you are on 10.10.1), put the 980 back in, and boot back up.
All is well for the moment, although Nvidia's link to cuda 6.5.46 for the mac actually brings up 6.5.37, but I'll tackle that tomorrow.