Vista power plans on P-7805u explained

I discovered this using a P-7805u with 9c.20 bios but this is probably the same on all P-78 laptops.

The only difference between the 3 power plans, balanced, power saver, and high performance, besides the defaults, is the clockspeed and voltage of the CPU. On high performance, the CPU is fully clocked all the time. The processor state percentage in the advanced options does nothing. In balanced and power saver, however, they do work to control the CPU clock, mostly, that is. The percentage you chose correlates to 1 of 3 different processor clocks/volts (these are governed by the bios and cannot be changed.) The first one is about 800MHz and .875 volts. The second is about 1700MHz and 1.025 volts. The third is obviously 2260MHz (and 1.0625 volts). When the minimum is set to around 0-20 and the max set to 100 on balanced, the CPU will jump clockspeeds about every second. This does not effectively cool the CPU or reduce power consumption by a whole lot. Fortunately, power saver only jumps to a higher state when it needs to, but it doesn't shy away from staying at full clock when running games and it doesn't hesitate to jump to full when opening an application like Firefox.

For those who think high performance mode is better for games, I benchmarked using Furmark for both power saver and high performance, and the results were nearly the same. (Power saver got a very slightly higher score do to random chance.)