How do I know if my CPU is dead, or my Motherboard?

My computer recently failed. if I unplug my CPU power cable (the 4-pin, 12V connector beside the CPU) the power supply revs up, the lights come on, the CPU FAN spins, but of course since the CPU power is not plugged in, nothing significant happens. I've already eliminated the power supply as the culprit, so how... show more My computer recently failed. if I unplug my CPU power cable (the 4-pin, 12V connector beside the CPU) the power supply revs up, the lights come on, the CPU FAN spins, but of course since the CPU power is not plugged in, nothing significant happens. I've already eliminated the power supply as the culprit, so how do I determine whether or not the problem is the motherboard or the CPU itself?
Update: With all power plugged in, memory removed, CMOS Battery checked and CMOS cleared, still nothing but a barely audible little electricity whine while the CPU fan moves a couple millimeters, then nothing. The MOBO LED is on, and with the CPU 4-pin disconnected, it "powers up" but does not beep whatsoever.
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