After upgrading to Yosemite, I noticed that graphics performance was starting to lag a bit on my 2009 Mac Pro while driving two monitors at fairly low resolutions. At one point I had two GT 120s running separate monitors, but after one replacement and two failures, I was back down to one.
I decided to look into upgrade options and was happy to see that OS X now supports non-EFI video cards. The only catch: You won’t see anything displayed until OS X loads your drivers. Who cares?
I settled on an EVGA GeForce GTX 660 2GB, which Best Buy happened to sell. I can feel the judgement from the hardcore nerds for buying something at Best Buy. Nevertheless, this was much cheaper than trying to buy another GT 120 to replace my second one and offers WAY more power. I don’t game on my Mac – I just want the OS to feel snappy and fluid.
Like many powerful cards, the GTX 660 requires the PCIe 6 pin power connector from the power supply or motherboard. I’ve ordered this, but until it gets here, I’ve rigged up an external power source.