Increasing AGP Voltage on 8K7A?

I have just begun to overclock on my 8K7A, and I've noticed one problem. My GF2U will not run 3D apps when running out of spec, such as 140fsb. I would like to try increasing the voltage to the AGP card, but I see no I/O or AGP voltage adjustment in the manual. I don't see any dip switches for that function either. Is this possible?

Although I am not familiar w/ the 8k7A, I check a few reviews and they all said that the AGP voltage can be adjusted in the Bios. That was one of the features that they liked.

Thanks. I will check it out in detail.