Oh, there's confusion here......................
Your PSU can not supply the power the system is calling for and the voltage drops.
Check this by connecting a digital volt meter to a spare 12v molev. Stress the computer and see how low the voltage falls. more than 5% is a potential problem.
Vdroop (the Cliff's version!):
When the CPU's load changes, the motherboard sends more voltage to the CPU. Since the motherboard's voltage regulator can't accurately change voltages at the extreme rates called for by the motherboard, some overshoot of the target voltage occurs. Vdroop just sets a lower target voltage so that the CPU isn't overvolted by the voltage overshoots by the motherboatd voltage regulator.
So are either Vdrop or Vdroop bad?
Vdrop: So long as it is less than 5%, is pretty much OK for everything except extreme benchmarking (wherein even a 0.05v change may kill an overclock!)
Vdroop: Great for everyday use up to pretty hard overclocks. It protects the CPU.
Fro extreme overclocks (i.e. LN2) many people like to controll voltages absolutely. Many of these rigs have altered/modified voltage regulators anyway.
Hope this helps..............