power supply problem with Gigabyte GA-7NNXP motherboard

Did you mean the PSU was made for "Compaq" computers? If so, those are trash. They work in Compaqs because the motherboards in those computers are basic models that require less power than a top-of-the-line board like a 7NNXP. If you want to strain your board and have it fail prematurely, or at least keep rebooting randomly, stay with the cheap ones. Personally, if I spend out for a board like the 7NNXP, I'm going to use a good PSU like Antec, Enermax etc. And I believe I would have at least 400W for that board.

Enermax are good
ive got the 465 watts model
love it!
but i changed the rear 80 mm fan in it to make it quieter though because im sensative when it comes to noise

otherwise its great
good rails too