My two macs are Sawtooths and both have 500watt ATX power supplies and the cables are very long and even have a few connectors that are not needed like the 4pin connections and a few drive molex connectors.

As for the backwards connections I was planing to remove the plastic portion of the connector or simply repin the power supply 20pin ATX connection. It looks simple to do on the drawing board but when I start on it, it will kick my butt a bit at first.