Hi guys just tried to upgrade my mac pro 3.1 by buying a kfa gtx 680 (pc) card and changing boot drive from hdd to the PCIe ssd i got. I used a kingston ssdnow 300, a velocity solo x1 pcie card and the gtx 680 card together but it won't boot. I cloned the original boot drive using Carbon Copy Clone. I plugged the old GPU in (ati radeon 2600) and could boot that way. I changed the boot drive by holding down the options key and chose SSD. It then booted. I then took out the old GPU, put in the new card and started it up but get nothing but a black screen. I then put the old HDD back into the drive 1 slot and it boots up again with the KFA card installed. Really odd, not sure whats happening. Seems as if the gtx 680 and ssd in pcie slots (both in the two x16 slots) don't work together. When it doesn't boot it reverts back to the original hdd bootable in drive slot 1. Any ideas? Somebody else have this issue?