I got a thermaltake TR2 RX 850watt power supply running (2) sata hd's, amd 1090t, 16gb ram, (1) sata bluray player, (1) PNY GTX470. I added another pny gtx 470 last night and after a few minutes my computer just shutdown on its own. Could it be because the powersupply isnt big enough to run all that and if so what size do i need?