How to repair video card for pc?

last week i buy a video card (nvidia 9600GSO) from low yat plaza and i intall it on my pc, at 1st is run good condition and every thing is so smooth, then this video card inside got 1 soft ware call Game Hub, this soft ware is to over clock for ur performance, then what i do is i set abit higher on that, after i set then i restart my pc, but after i restart on it then evry thing is run so slow and hang so time, then i try to reset back, but it cant go bk to the default, then i try to reformat my pc coz my pc is really run so slow and not preforming well, but after i format and instal bk the driver the same problem is still there evry thing is so slow some time i not even can start my window.. i think this setting alr set in my video card but i cant restore for that, do any one here can help me to sove this problem??|||If you have already started over and it's not a big deal, take the card out, reinstall...then install card and set it up like before, when you OC you use more power, so get a bigger psu then OC...also check what tweak windows a little for better performance, see my tweak vid on youtube http://www.youtube.com/MEGASPARKs