|Does your power supply have a 20 or 24-pin motherboard connection? The extra 4 pins doubles the current capacity on the 12 volt rail:|
which may be necessary if you're using a PCI-E card. If you're not using a PCI-E card the PSU will not need to supply as much current at 12 volts and maybe the 4-pin power connection for the cpu won't be necessary. Still, even in that case attaching the 4-pin connector shouldn't cause a problem.
If it seems to work OK without the 4-pin connector attached then I guess leave it that way. If it's powering up but nothing is showing on the screen then that's something else---motherboard, cpu and/or power supply.
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