yea, welll had a look around upto 3.7v appears to be safe. The reminds me about the 3.7v VIO jumper my old Asus TUSLC2 pentium 3 board I had.
Even though raising the 3.3v didn't get me any higher vdimm, it did however stablilize my memory overclock, was able to run slighty high and tighter without errors.
Would recomend this mod, very very simple. Just cut the orange 3.3v sence wire(im my case) on the power supply, put in a 10k VR to ground, and ya done.
Guys, when overclocking a higher 3.3v gives you more stabiliy. I wouldn't run 3.3 so high. I would run it at 3.5 for 24/7 use. But if you insist on running it that high, make sure you use a molex for your SATA and not the SATA power cable since it runs off of 3.3v.