Peculiar power draw (GPU Mining)

[mikk2k2]

Hey guys/girls.

Trying to figure out something with my miner. I've got 5 x 7970, powered risers, MSI mobo (Z77A-GD65) 8gb ram on win 8.1

One of the x1 PCI slots on the motherboard runs at a lower voltage than all the others - so the card runs at 1.10v as opposed to the other 4 that run 1.17v. Which ever card is in that slot runs at 1.10v. I'd like to undervolt the card but I can't (Hardware locked) but it seems that the motherboard ports could give me what i'm looking for. Has anybody had similar experiences?

Any help appreciated!