One of the advantages of that 900 Watt power supply on the older Mac Pro is that it could drive and POWER eight 30 inch HD monitors without batting an eye, while doing live rendering light ray tracing to each of them of a different animation scene. Of course that power supply alone would set you back around $600 if one were to try and build an equivalent PC at the time. I priced that out. A lot of critics were claiming they could build an equal system with a $40 P/S.
Yeah I know - but it is a $ issue with the wattage. Love to have one but just draws too much current for my now limited needs.