Until I moved to here I had not been paying for the electrical power I was using and my hut was heated by electricity anyhow so I didn't care much about the power my computer was consuming in the winter I even used my computer as a heater by running the CPU at 100% while working on the project Seventeen or Bust.
Now I have moved a place that is heated by a central heating system running on wood, I don't pay for the heat but I pay for the electricity I use so I have been trying to change a few things.
My investments in 2 P4's while living in the little hut seem a bit annoying now, I have been selling the smaller of them and now only have one system running.
I have activivated the CPU-frequency scaling in the kernel, which means that the CPU will scale down when there is no need for running at 3GHz, it is scaling down to around 400 MHz I notice a little delay in scaling up, but that is not something that annoys me to much, a bit of fine tunning of this system and I have quite a bit of power saved.
Anyhow the P4 is still eating too much power, but for the time being that is the best fix I could come up with, I don't want start investing in new hardware right now.
I think I would do well to invest in a better power supply with the 80 PLUS specification, which would allow my power supply to better follow the demand from the system instead of it being a bit conservative and eating to much power all the time, until I have that kind of power supply I don't think I will see the full effect of the frequency scaling.
Another big problem with my desktop system here is the two old CRT screens I am using for my dual screen setup, I surely would save a lot of power replacing them with two LCD's or maybe even better one big LCD (not sure about that though, I think I might get better watt/squareinch with two smaller LCD's). As I wrote earlier I don't want to make any new investments, so for now I try to remember to shut down the CRT's when I don't use them.
I am sure I will find other ways to reduce my computer power use, I will try to post about it here when I find them.