So I installed a used CPU after installing bios update from Asus, the CPU is compatible with mobo. I started it up and it went to bios after recognising new CPU everything seemed ok and then it restarted and shutdown and won't start up again, it starts up for a brief second then shuts down every so often it starts up but I can't access bios it just runs if that makes sense. I've tried to reset the CMOS with switching the jumper etc, I've got the mother board out of case doesn't make a difference I've left the battery out as it's probably dead however I don't think it would matter? The old CPU doesn't change anything either. Just wondering if anyone could shed any light on this whether it's the PSU or any other hardware that's conflicting with it or what a possible solution would be? Asus P8Z68V-LX. i5 3750. 500w PSU