Is your monitor showing a message similar to "No signal" when it is turned on with the PC 'on'?
If it does then this would point to a problem relating to the gfx card and the monitor itself.
Otherwise what gfx card do you own, because if it is a high end gfx card, then your power supply is too small to support it. Just to check that your PC is booting correctly, remove your gfx card and plug the monitor into the VGA port on your mobo and check to see that the computer is booting normally. IF it doesn't, then it would point to a motherboard issue.
Serunson
Posting Maven
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This sounds like the CPU is not recognised by the motherboard, but it does detect there's a CPU there.
If it's a new CPU it likely means it's too new for the motherboard (but maybe flashing the BIOS will solve it), if it's an old machine the CPU may be damaged and need replacement (which may also mean replacing the motherboard if you can't find a CPU that fits it and is recognised by it).
jwenting
duckman
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