When it comes to global power consumption, the system doesn't seem to need more than 350 W (meaning 300 W for the configuration itself once we subtract power supply losses). Nvidia recommends a power supply with a minimum rating of 580 W, but we consider this to be overkill. Even when future games are able to make better use of quad-core processors and graphic cards, a reliable PSU that delivers a constant 450 W should be more than adequate.
AMD's Radeon HD 3870 X2 yields similar results to those we've already seen with the HD 3870 (when compared to a 9600 GT); its power consumption is low when idle (18% lower than a 9800 GX2), thanks to the use of a 55-nm process and more aggressive clock gating. However, the outrageous raw throughput of the 3870 X2, resulting from the number of stream processors when its power consumption plateaus, means that it demands more power than the newcomer, despite performance being 37% lower in this game/mode. Its performance-consumption ratio remains 40% higher in this case.