Here is small entry about how to do Voltmode using onboard jumper and where is Vcore monitor points.

1 2 3
o o o = ~1.11V
[o-o]o = ~1.25V

o[o-o] = ~1.35V

From my own experience I was able to switch Vcore on the fly. Provided image below will give you possible point where you can measure you Vcore using multimeter.

Pretty good tool to test stability and benchmark when overclocking.

Recently I got new video card! Definitely first thing I did - overclock it. It has great overclocking memory Samsung 1ns, allow works stable at 2200Mhz, but core overclocking is very weak, max I can get is 720Mhz :( Also using Riva Tuner I overclocked shader domain to 1900, work stable, in ATI tool in 3d mode I noticed 20% FPS increase when 700/1900/2200, but playing with shader really doesn't changed a lot of fps. But in 3DMark06 - yes.

Overclocking statistic:

Hey, do you wan to see how looks installed Accelero S1?

Look here:

I installed it at my Evga 7900GS, threw away stock cooling !

Now I can do overclock it to 640/860, 39 Idle / 48 Load!

But Accelero S1 is huge, compare to all coolers I had before, - this beast takes lots of space inside my case. Here is closer look.