Ever since i got this new motherboard and CPU ive been having a bit of a nightmare with it. Gigabyte ga-ma790fx-ds5 -Latest Bios AMD Phenom Black Edition 9850, 4 gigs PC 6400 ram (Corsair XMS2 CM2X1024-6400 ATI Radeon 4870 The problem is that the motherboard will NOT power up at all with the 2 of the latest power supplies (600 watt+) i have. It wont work at all with; (Nothing happens its just dead) Arctic 600 watt Jeantech PSU (brand new and working) Corsair 620 watt HX PSU (working) It only seems to work with my Jeantech 450 Watt PSU and i cant for the life of me figure out why. Ive tried everything to get the board to work with the new PSU's. I had thought that the PSUs i got were dodgy but after testing out one in an older PC it worked fine. Ive removed all parts and tried powering up and i cant get it to boot up. But the PC seems to work fine with the oldish 450 watt PSU which i find just unbelievable. Can anyone help with this nightmare? Now on the Gigabyte site the CPU i have isnt listed as supported by this motherboard which is kinda worrying could this be the reason? If so how the old PSU boots up. I just want to have the fracking thing working with the right PSU.