GTX 950 with 10.8.5

[Going Bald]

How? I tried a kext and it didn't work. Seems like the only way i can boot the system is with IGPEnabler=No GraphicsEnabler=No nv_disable=1

Remove the gfx card. Connect display to a DVI or HDMI output - VGA blue DSUB connector will not work. Boot to BIOS.
In BIOS, set first init display to internal graphics - may be listed as IGP, IGFX or something else depending on BIOS. Set igfx memory to 64M. Save&Exit. Continue boot.