There is not much question that you should be running IRIX on that unit. While *BSD and Linux will run, the vast majority of the unit's special hardware are not supported. Even recent versions of IRIX (6.5.16) are fairly easy to purchase on eBay. As for the power, it should be a non issue with an R4400 based Indigo2. At various times. I've had several Personal Irises, an Indy, an O2, and an Octane. The only unit that draws a lot of power is the Octane with its 800 watt power supply (which it seems to turn into nothing but heat).