|Your clue that the processor was OK was the beep code for no video card. If the CPU was bad you would get nothing at all. You bought lots of hardware but you should have started with the power supply. |
When you installed a working board into the case did you then connect everything up to it? Your should not do that.
All that is needed to POST are the following: Power supply, motherboard with CPU/HS/fan, 1 stick of RAM in the first slot, graphics (onboard preferred), monitor and keyboard. Computer should POST to an error stating no bootable device or something similar.
You then reboot and immediately enter the BIOS screens to check voltages and temperatures. 3.3V, 5V & +12V should all be within +-5% of those numbers.
Add in devices one by one. As riider stated above, you may have a short. If you have a cheap case that doesn't use screw in standoffs but has raised bosses stamped in, you MUST use insulating washers between the board and the case.
If your case uses metal screw in standoffs they MUST be installed under every screw hole and ONLY under screw holes. Standoffs MUST also be the correct length. If you have to force the board ports through the back plate them you may not have the correct standoffs installed.
A defective CD or hard drive can keep the computer from POSTING. Also, connecting additional hardware wrong can cause the same issues.