Term for a powerful personal computer?

What term would an enthusiast use to describe a powerful, tripped-out personal computer, the kind he might custom-build in his garage and overclock to the max?

The usual reference sources are failing me here, as I'm looking for a slang/jargon term.

The closest I've found is rig (as in "gaming rig").

I think rig is fine here, but I've also heard box or build.

You could combine the common geek term uber, for uber rig or uber box.

The owner of this rig would tell you that it screams.

Ars Technica produce regular system guides (here's the latest) in which they recommend the best gaming rigs you can build at different price points. They call their systems:

• cheapest: Budget Box
• mid-range: Hot Rod
• no expense spared: God Box