i got a gygabyte m61pme-s2 mainbord, amd x2 5400+ dvd-rw, hard drive ,asus hd4750 ,and ez cool 650w psu, the pc is cuting out every now and again , cpu temps in the bios read 80c after it's cut out, there is no shutdown warning or temp to shutdown set, is this a psu issue or is it over heating ?