Do they run fine? Do they lag? If you suspect you fried your card it's best not to use it... And by the way... what kind of card was this that you were trying to overclock to perform in CS and Warcraft?
There are not any real diagnostic tools for a graphics card, at least not any bit by bit mem testers or instruction testers for gpu's. If you did fry it during an overclock, which I doubt, you would notice constant 2d and 3d artifacing.