Power consumption

We tested the complete power consumption of all systems at both idle and load. Load means the highest power draw spike ever observed during benchmarking.

The NVIDIA numbers are lower than what I expected, especially after all the talk about monster PSUs. This shows that NVIDIA has done a great job keeping the power consumption of their GPUs down. Another factor might be that the memory and engine clocks are reduced.

It surprised me that Crossfire consumes such enormous amounts of power. After a quick phone call with ATI I was told that the X1900 has a bigger die, so more heat output. Also the new ring bus memory controller takes up a lot of space and generates "unnecessary" heat because it is not fully utilized yet. However, as I am told the design was an investment into the future and will pay off in the next years.

Please note that seeing ~450W here does not mean you can use a 450W PSU with QuadSLI. Most PSU manufacturers are very optimistic about their Wattage ratings. Also there may be problems with the 12V line not being able to supply enough current on such models. My educated guess is that you should be fine with a high-quality 550W PSU, but better spend a few extra bucks to not have even more problems because of the power supply.