How true, My original comment about rapid swings in supply current are about 6-7 years old. I got it from a discussion I had with some AMD engineers during the clock speed wars with Intel. They were talking about how PSUs now had much higher current slew rate requirements (AKA response time) then then previously because of the higher clock speeds and strategies being employed to lower system power requirements.On a bright note today's processors use considerably less power to do more work than their counterparts of a few years ago. This results in less heat being generated by the CPU. Intel has dozens of white papers on that subject listing the power demands of their CPUs.
Since the speed wars ended, there has been a quieter war going on to lower supply current due to efforts to capture more of the notebook market and now portable devices (and Green pressures more recently). Since lower supply current isn't "sexy" from a marketing POV, we don't hear much about it but the executives who make choices about what to put on motherboards are keenly aware. Smaller feature size and things like dual and quad core processers have allowed this current reductions. To see a really hot CPU you might need to go back and look at a single core 3Ghz system a few years old.
Relodron, that was a good example. I may look at similar performance specs on my own P4 celeron system this weekend, I don't have as many internal HDDs though. You might be able to push the power a little higher by running a defrag along with those three clients. And you're absolutely right about high performance GPUs being power hogs (at least for rich gamers).