one of the key specs for power transistors is operating temperature. When near the top end of dissipation, the case can be past the temerpature of boiling water and still be able to dissipate 60% of what its top rating is (typical for 2N3055 power transistor anyway). If you want to make absolutely sure, then get the part number and find the specs on it. Measure the case temperature and then the emitter and collector voltages. The difference between the two times the output current of 7.2 amps will give you the wattage it is trying to dissipate. Refer to the specs to see if the temperature vs dissipation is within spec. A simpler solution is just run it and see if it eventually blows up... (it is probably okay) best regards, Steve Thatcher -----Original Message----- From: Bill Sudbrink <wh.sudbrink(a)verizon.net> hot to touch. Is that normal operation for this kind of supply? Maybe I got a bad one from WeirdStuff? Or could this be some additional clue as to something wrong somewhere else in the computer? According to my meter, the voltage is spot on 5 volts and the current is 7.2 amps. Any suggestions appreciated.