I think I've experienced every possible problem because this one has me fooled! Background: Started 4 months ago as a display problem. Sent ATI AiW 9700 in for replacement, received AiW 9800 Pro. Did not resolve problem. Sent in Asus A7N8X-Deluxe mobo in hoping it's a faulty AGP slot. Received replacement, but it did not resolve the problem. (FYI Yes I did try another monitor). I sent in the CPU to be replaced, since the problem occured before POST. That seemed to fix the display problem for now, but Windows XP would not boot! I wiped the hard drive and reinstalled Win XP, but then, my computer would boot either to the Win XP boot screen or to the POST report screen before it, then the computer would reboot itself. I then decided to replace the RAM module, purchasing a Kingston 512 MB DDR SDRAM stick, first installing it by itself, which did not solve the problem. Then I installed both sticks, and that did not fix the problem. I pulled out the old stick and powered the computer, and now the computer will not even POST! Lights and fans turn on, optical drives start, but no POST beep or anything in the monitor! It's not the PSU because I replaced that recently (Antec 480W). So, I guess all that's left is the hard drive, which I assume is physically damaged in some way? But shouldn't my computer at least POST? What do you think is wrong? This problem is soooo frustrating!!! Scott Jung

sounds like the psu to me

disconnect all cards, ram except video card & 1 stick of ram. remove all cables from drives. reseat video card, ram & motherboard power connector(s). clear cmos chip. check all cans(capacitors) are flat top not domed. repower system. if still having post problem remove & isolate board from case to use psu. post results david