MSI Afterburner - Core Voltage OC Problems!

Hi everybody!

I recently bought a brand new gaming PC, after years and years of being a notebook gamer.. So, i finally decided to play around with the overclock settings for my GPU

I have the Z77 MPOWER Motherboard, and as for my GPU, I have the N680GTX Lightning. My system is running windows 7 x64. I use MSI Afterburner 2.3.1 for applying the overclocking, and Furmark for testing (instead of Kombuster)

Im all new to overclocking, so i started reading about it, and came across this review of the GPU:
http://www.xbitlabs.com/articles/graphics/display/msi-n...


And they clearly figured out some nice overclocking settings for the GPU. Allthough, I didnt know if I should just change the settings to those levels right away, so i kept looking and found this post as well: (reply #4 was the interesting one for me)
http://www.overclockers.com/forums/showthread.php?t=687...

So i started to slowly apply the overclocking to my Core Clock, and everything was well. I was able to get it to +70/80 before the drivers started to crash. But then i went ahead to apply the Core Voltage overclocking (slowly increasing the Voltage a little bit at a time). But then i realized, that when i increase the Core Voltage (to ex. +12 or +25), nothing happens to "GPU voltage, V" in the monitor screen. It just stays at 1175'ish. When i increase the value and press "Apply", it drops to 1100 for like 1/4 of a second, and then goes up to 1175 again. And no matter how much i increase the Core Voltage, it just wont go higher than 1175. When i apply the overclock, GPU-Z also says that the GPU Clock "boost" still is at 1176 (Just like the Defualt Clock). Now, I did increase the Power Limit from 100 to 133%, and i checked "Unlock voltage control", "Unlock voltage monitoring" and "Force constant voltage"(don't really know what the last one does, but i have the same problem with applying the voltage overclock whether i have it checked or not). I also set the UAC settings to "disabled"(Never notify), as i did read somewhere that that could be the problem. Didn't help me though..

Is anybody else experiencing the same problem? Or does anyone have any idea of what i do wrong? Hope somebody can help me!  

(this is my first post in here.. And sorry for any bad English language)