That's a good note, but I did mean the computer's input voltage, not the CPU's. You can increase an individual neuron's firing speed plausibly trivially, but the brain (like the computer) is a complex regulated system that can't be played with that way without causing problems.
Okay, fine -- but bear in mind that there are computers which run everything, from the CPU to the memory to the I/O, off a single (variable) input voltage. Most microcontrollers, for example, meet this description. I googled one at random to get some specific numbers; the PIC18F4550 runs on anything from 2 to 5.5 V, and this is not unusual.
Okay, okay, you got me. I'll concede the point entirely :) Feel free to disregard the analogy as it applies to computers which may be made to run faster by raising the input voltage.
