Its probably your psu hook up a multi-meter measure the voltages if there more then 10% off what they should be buy a new psu, problem solved.
Red wires are 5V, yellow wires are 12V, orange wires are 3.3V. Black is ground.
Btw a easy way to avoid all this testing. Is just looking at the sticker on the side of your psu and if the 12V+ if that rails rated for less then 27A then your psu can't power this card and will probably blow if you keep up using it.
edit: Btw don't worrie much about temps
As long as you have a normal case with atleast 3 fans the air flow should be enough to keep temps low enough so it doesnt artifact.