Yeah, kind of unusual I know, but I have a situation where I need to know if I can save a significant amount of wattage by underclocking an older 478 CPU I have a couple of old Asus P4-C800E-Deluxe boards with 3GHz 478's on them. I use these strictly as servers to grab OTA HDTV signals via tuner cards and BeyondTV front-end software. I am also making the following assumptions: The CPU and Hard Drives draw the most power. The CPU is not really needed because the tuner cards don't really do anything but strip the carrier wave away and send the .TS data stream to be recorded to the hard drive. Finally, using suspend or standby is not really an option, as BTV is not able to reliably bring the hardware out of resting mode to start recording a show. Finally, the systems function fine on old 5200-series AGP graphics cards as they don't handle any real decoding chores. I think I am about as stingy as I can go in the graphics department, as PCI-based cards are not an option. Now, I assume that all other things being equal, a 500GB HD needs about the same amount of wattage to run as a 1 or 1.5 TB drive. I am pretty much maxed on HD size at this point. But, if I underclocked my CPU by say 50%, would I net much in the way of energy savings, or not? Also, do all power supplies draw some base amount of wattage when they are turned on, regardless of the load presented to them? Any info would be appreciated.