Ok I was right, a shame it broke though. For the next psu, try to get one that has only 1 big 12v line. Also for every psu I buy I google the model and review. I look for a good stress test and read how it went, the thing you gotta look for is how it handles a full load for a long period of time. You have to think that you will use the psu 24/7, a cheap one will fail on you.

pd: I'm running 4 280x under a 1200w gold coolermaster and it runs just fine. To run just two cards a good 850w psu will do.