New Graphics Card -- Can't boot!

So I'm working on my first hackintosh, and I just got a graphics card after using integrated graphics for a while. My computer worked fine beforehand, and I could run OS X without a problem. I got the EVGA Geforce GTX 950. It fit into my case, the Fractal Core 1000, without a problem, and I got it hooked up. I can turn on my computer, get to the clover boot screen, and boot Mac OS X, but while the bar beneath the apple logo is filling up, my computer crashes, and restarts within a few seconds. I changed the BIOS to disable Intel Processor graphics, and now when accessing the BIOS I get an option to choose a boot device, which didn't happen before.. Booting with -v or GraphicsEnabler doesn't change anything, but booting with -x gets it a little farther. The crash doesn't seem to be random, and verbose mode doesn't give me any warnings before it happens. I tried booting the recovery partition, and that almost booted fully (4/5) but then crashed the same way. My power supply, a 550 W Corsair, should be enough to run the card. Any ideas? (Sorry for the long post, just wanted to clarify everything I've tried so far.)

My specs are: Mobo:gigabyte Z973-D3H Graphics: EVGA GeForce GTX 950 2GB GAMING Cpu: Intel i5 4690k Power: Corsair 550 W