The difference in power consumption between an idle CPU and a maxed-out CPU is appreciable. I stopped doing Folding@home, distributed.net, etc when I discovered

The difference in power consumption between an idle CPU and a maxed-out CPU is appreciable. I stopped doing Folding@home, distributed.net, etc when I discovered my old AMD 2500+ sucked an extra 30 watts when pegged. That was a desktop chip! I suspect it's even worse with the new mobile=>desktop chips these days. If electricity is free and you don't care about inhaling more mercury due to coal burning, go ahead and run it all you want.