A friend has brought their computer to me and told me it doesnt work. The computer turns on and I can get into the bios fine but it wont load the OS thats installed on the HDD and wont boot from CD either to do a re-install. I have ran memtest 86 with 4 passes, so the ram is fine. Tried 3 Hard drives (2 of which are known to be working) and 2 DVD drives (one loaded the memtest cd so presumed working?) I have stripped it down to the basics and is out on my desk with PSU, MB, CPU+Fan, Ram, GPU, 1 HDD, 1 DVD. Im at a loss to what this could be, any ideas?