Fill out both sides of this form and see how much power you need to run your machine.
Always figure more than they say.
Very cool link.
Poer supplies are heat generators. Therefore cooling concerns shoud increase with power. There are external power supplies available that neither take up the internal case room, nor generate the internal heat. Expernal power supplies designed for rack mounts are widely available at reasonable prices. I am a radio engineer with a few decades in design and service. Heat is the electronics "killer".