maybe theres something wrong with the GPU.
i think that even if the card is fried, the fan still spins.
Either get this, and see what the post beeps tells you, unless you already got one that has post beeps.
i dont know where to get one though... i got mine from my case.
Or try to get your hands on a graphics card, maybe from a friend or something.
EDIT - you can get it from here, but i never shopped at that site before, so i dont know if its safe or not.