cerebus
Honorary Master
Overclocking doesn't impact the power draw, but overvolting does:
From a couple of other places I've also seen that volt tweaking it has a disproportional impact on draw.
LinkUnlike overclocking without overvolting, which saw fairly negligible increases in power consumption and thermal output, upping the GPU voltage, even by such a small amount as 60 mV, saw the power consumption rocket. When overclocked and overvolted to its maximum stable level, the MSI caused our test system to draw 343W from the wall; an increase of 20 per cent over the result using a standard GTX 560 Ti 1GB.
From a couple of other places I've also seen that volt tweaking it has a disproportional impact on draw.