This could be as simple as a HDD problem, I dont see in your novel above where you tested the HDD. All you say is you get no OS. But you do get video and the ram check completes.I would see if you can boot off a boot disk. If you can get this far it would seem prob may lie else were. Find out what brand drive you have and download the diagnostics off of the manufacturers web site and boot from it and run it , it will tell you if your drive is bad. If you have checked the HDD, please disregard.