So, we have power, but no POST.
These always suck, since there's no easy way to determine what's causing it.
1) Remove the CMOS battery from the motherboard (silver thing that looks like a watch battery). Wait about 5 minutes or so, then put it back in. See if it POSTs. If it does, great! If it doesn't, then...
2) Unplug/remove everything from the motherboard except for the following:
- Power supply
- CPU and heatsink
- One (1) stick of RAM
- Video card
See if it POSTs. If yes, goto 3a. If not, goto 3b.
3a) If yes, then add one item back in at a time, and see if it POSTs. Rinse and repeat until either everything works (you're done!) or the computer decides not to POST.
If it doesn't POST, then
a) The component you added in probably caused it not to POST (replace the component in question)
or
b) Your power supply finally hit its operational limit after adding that one component...if so, there may be some merit in someone's frequent (and often patronizing) suggestion in using a multimeter to test your power supply. If the power supply ain't working like it's supposed to, then replace the power supply itself.
3b) Switch the stick of RAM out for one of your other sticks, if applicable. If it works, you're done! Replace the bad stick of RAM. If not, then goto 4.
4) Switch out the video card for another one compatible with your system. If it works, great! If not, then...
5) Switch out the power supply for another one compatible with your system (that's the only thing left other than the CPU and motherboard). If it works, great! If not, then.
6) Remove the motherboard from the case and put it on top of a cardboard box (do NOT put it on top of an anti-static bag--the outside of an anti-static bag is conductive--the inside is insulative). Plug in your power supply, video card, and a stick of RAM and see if it works. If so, great! That means something between the motherboard and computer case is causing a short. Find out what it is (a stray piece of metal, a gold standoff that's not aligned to a screw-hole in the motherboard, etc.). Once that's resolved, you're back in business! If it DOESN'T work, then it's probably the motherboard (it could also likely be the CPU--if you have a spare CPU that's compatible with your board, by all means try it, but if not, don't worry about it).
