Largon, I was initially measuring at those points, that's where I measured 1.23V. However, I also measured 1.15V on some of the little capacitors closer to the GPU. 1.15V seems like a more reasonable stock GPU voltage, but it also seems like they would put the big caps on the main power supply, so I don't know what to think. Are you sure those points are the correct ones to measure?

As for my voltage mod, I actually modded the memory voltage instead of the GPU voltage. Doh!

The DC-DC converter for the GPU appears to be a Richtek RT8802A on the front of the board, which I had originally assumed was a Realtek 880 HD Audio codec chip. Looks like a VR from pin 4 to ground will do the trick. Hopefully it's actually the correct chip this time