Video card voltage is too low....

A while back, I built a tri sli system using: (shortened, since not important to the central question.)
q9450 @ 3.5
4 gigs ram
corsair 1000w psu
tri sli gtx 260's
780i sli mobo

Initially, I had two gtx 260's. After the price on the gtx 260's dropped to 150, I bought a third and installed it in the third pci-express x16 slot (the middle one) on the mobo. After testing, my framerates were higher but not as high as I had hoped. I assumed that the reason was simply bad sli scaling due to the quad core. (i7 scaling is superior.) Recently, I opened gpu-z and noticed that the voltage on the card in the center was much lower than the voltages on the top and bottom cards. This got me wondering if insufficient voltages could be the reason for the issues that I was having. Since my other two cards are already at the voltages that they should be, I was wondering if anybody knows of any programs that allow you to adjust the voltages independently? I just need to push up the voltages on the central card to the levels that the other two are running at. (I looked it up, the central one is being undervolted.) I'm hoping that this will boost the performance up to the levels that I had been hoping for.... I don't know if it will work, but its work trying. Any suggestions would be great. I have already tried the evga voltage tuner, but it can't adjust independently....