I picked up a Swiftech thermoelectric heatsink for about 1/4 of its original price (about $20) and I'm planning out how I'm going to set it up to keep my old Athlon XP 3000 a little cooler than it is right now. The thing is a monster. The cooling element can eat up to 226watts, which to me is just stupid, so I'd like to come up with a way to automatically control its power consumption based on the temperature of the CPU die. It would be nice if my motherboard had temperature-controlled fan sockets, because then I could use a simple power transistor to use the voltage at the fan socket to control the much larger power feed into the cooling element, but my fans run at full speed all the time so that's not an option. I'm going to have to measure the CPU temperature externally, using a flat thermosensor of some sort, but then the problem of how to use the thermosensor to control the power to the cooler crops up. There's no way I could pipe 200+ watts through a thermosensor -- I'd destroy it AND the CPU it's attached to. So what I need is some sort of magic box that is designed to accept input from a thermosensor and use that information to control a high-speed fan. The cooler is 12V, so matching the power supply won't be a problem, but the magic box will need to be able to withstand up to almost 20 amps if necessary. It would also be nice if the magic box could be programmed, so I could set the temp-to-voltage map myself. Does such a thing exist? Where can I get one?