Hi Tony, That's what it is. Transistor(s) acting as "regulator" controlled by microampere regulator like Astec '431 in a TO-92 (ie found on pcchips boards), or usually by (usually national semi.) 2951 IC. That D45H2 explains the 10A rated. P5 cpus draws about 3A or less for sub 100mhz, 100 < 150 is about 3A to 4A, 166 and 200 is about 4.25A and 4.6A. Don't forget: chipset, cache draws on this 3.3V current as well. But! Linear regulators are inefficient at channeling from 5V to 3.3V, very often mounted on too *small* heatsinks or in poor or stragent airflow. That is why they run hot enough to make one's fingers jerk out with a owch! I have swapped or robbed other boards for good power transistors in that design about 10-15 times. That is very common occurance. They just simply blow for no reason. If a chip is really bad it will heat up like crazy but not that sudden death in linear regulator except if it's really aged and on the edge and adding that cache stick pushed it over. And failure mode is shorted and externally usually no sign of failure like holes or smells. This is why m-board makers have since converted to switching inductor regulator design for reliablity and more current capacity around '95-96. Very little heat, most of heat if any is from coils. Failure very rare in my experience regarding those switcher regulator even in cheapo boards. (!!) PSUs in laptops used same idea and often mosfet and like doesn't have any heatsinks at all or just very modest one. Look into notebooks, pii/piii/athlon/ss7 boards for that examples. Wizard