Hello! I received a free iMac with a dead PSU. Ordered a new one, taking eons to arrive. On these acrylic models, the PSU hooks up to a board which does most of the 'heavy lifting' as far as power distribution goes. Going to the board (via a molex-esque connector) are 5 wires, 12V, 12V, GND, GND, and PWR_OK. I simply cut off the connector from the old PSU and elongated the wires with some wire of a similar gauge. Then I grabbed a junk ATX PSU (doesn't supply enough voltage though the ATX connector) and chopped off two molex connectors, for their 12V/GND. Soldered it respectively (white/yellow to gray, black to GND two times over) and left the PWR_OK line to itself. Powered up fine and went on its merry way .