"I wonder what Carmack uses now? Whatever it is, he could probably have several of them hooked up to a machine each running at 1920 x 1080 and still come nowhere near close to drawing 180 watts."
That's a little optimistic. The 27" and 30" TFTs which are becoming increasingly commonplace consume upwards of 100W, at least at or near full brightness so you'd only need about 2.