What type of processor is it? Is it an Athlon, Duron, Pentium III, Celeron? If it is an Athlon chip your power supply has to have a GTA rating of at least 42 to turn the chip over upon startup. that could be one problem. One test we run at the shop is to uplug EVERYTHING, I mean everything, IDE cables from drives everything. The only thing you leave plugged in the is processor, video card, and ram, don't even plug in the keyboard and mouse, just the monitor cable and see if it posts. If it doesn't then it's the video card, ram, processor, or motherboard. After that it is just a trial and error process to see which component it is. Now if it posts then it means that you might have a bad IDE cable or a bad hard drive, CD-ROM, or floppy. IDE cables rarely go bad but it has happened as well as floppy drives, and HDs, and CD-ROMs. But if all else fails try replacing the power supply to a 250 or 300w with at least a 60 GTA rating. Hope it works out for you. PM if you get it to work.