The PSU can cause problems with graphics by not supplying enough power to the GPU, but here I'd say the graphics card's definitely the problem.
Sadly, you may have fried the card by turning it on without letting it dry sufficiently. I've had iPods that partially revived weeks after going through the wash.
Leave the 260 alone for another week and then try it again. If you get the same kind of problem, go get a new card.