How can I overclock this card Geforce 6600GT 128?

First download the reg hack to get it to overclock

http://downloads.guru3d.com/download.php?det=815

now you can right click on your desktop and click on properties then settings/advanced now you will have a slider bar there. Move it slowly starting with the core, then the memory untill you see little white dots on your screen. then move it back a little bit and there ya go.

thank alot but htis is the new version and it diff then wht u told me to do. any way i THINK i got it to work lol..it can overclock on 2d and 3d..

it wont matter if it is the newer version. It just adds it to the registry. And you can overclock anyone you would like just be carefull not to overclock to high or it will fry your video card.

on 3D mode
550 mhz for core and 1.0 ghz for memory
is that a good or fine or bad setting?

no thats a verrrrry bad setting guarnteed to blow up your video card. Only go up by about 5 points at a time on both. Not that big of a jump...