So which slot do i use? PCIe 2.0x16_1 (blue at 16link) or the PCIe 2.0x16_2 (black at x 4 links)? I have my 7950 vapor x installed in the black but it is very very close over the PSU. (friend said use the black one). If I used the blue it would give my gpu a lot more air room but IDK the difference please help!