Getting 4th GPU to Work

[bitbaron]

Hey All,

Having some trouble trying to get the 4th GPU in the PCI-E 1x slot running in my mining rig, but not having much luck.  (And then maybe a 5th if I'm luck)

Here are the details

Board/CPU/MEM: Asus P8Z68-V Gen3 / I5 2500K / 8GB
PS: OCZ ZX 1250W
GPU's: XFX 7970 and Gigabyte 7970 (both with 6pin and 8pin power connectors)

2x of the GPU's are on 16x risers (1st and 3rd 16x slot) and 1x GPU is seated in the board.

I've tried to use both PCI-E 1x slots but the card never shows up.
I've tried the wire jumper, plugging in molex connector on 1x to 16 riser.
Set PCI-E to 1x in the BIOS.

I'm out of ideas on what else it could be the issue.

Any help is appreciated.

Thanks