...your life....and the life of your Graphics Card are now both about to end...!!
Lol, don't be such a sook F.
I modded my 7900GS bios as soon as I figured out the max stable overclock for it and it boots that way for the last year or so, ever since it was 3 days old. The video bios boots it at 650/825, down a pinch from my max obtainable clocks which were around 710/895.
This card has no volt mod or anything else and it runs cool as can be, rarely going much over 50*C
To overclock:
You can download coolbits2, It seems to work with the latest drivers, but I'm suspicious that the latest drivers have the overclocking function enabled, you just need to find the settings in the control panel.
This sounds a little confusing, well, I used to use coolbits (it's just a reg key hack like clicking a shortcut) and then one of the recent drivers reported that I would have to install ntune, which I did.
Since then, I uninstalled ntune, installed a new driver and the overclock functions work.
So, I'm not sure if the reg key is still enabled, however, a friend who just installed a new driver found the overclock functions enabled with no further action.
The function will test your settings before it allows you to enable them, and you can start the overclock at bootup if you wish, I just modded my bios so i didn't have to do anything ever again. If you have a gigabyte 7900GS, I can write a bios file for you once you figure out the clock you want, if you wish.
cheers!