I know it's a pretty sketchy power supply already, but do you think this would be able to run a single 680. I read the 680 requires 38amps and my power supply has 2 12v 24amp rails I'm wondering if this is sufficient... thank you
It should be enough as the PSU states it has 741W total on the rails, and the amount of power is about half again what you need, but it doesn't have APFC (which while not a major problem on it's own is a bad sign) or any form of 80PLUS testing. I can't find any reviews on it either.
Yours however to put it bluntly a horrid PoS. I would replace it, even a 500w model is more than enough for a 680 + any cpu. Since you have the cash for a 680 you really should replace it man. You could also drop down to a 670, overclock that, then spend your savings on a psu if you absolutely have to stay in budget.
170w x 3 = 310w + 190w (lets assume heavily OC'ed i5 3570k) and thats only at 400w. (lets then assume +50w for drives and fans.)
Edit: according to qbsinfos benchmark link it appears a 700w might not have enough power to run 3x 680s but you get my drift nonetheless.