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Power, Heat, And Efficiency

System Builder Marathon, Sept. 2010: $2000 Performance PC

We knew that two GeForce GTX 480 graphics cards would hurt our power consumption numbers, but we had no idea that this system would pull over 1000 W when overclocked. 80 PLUS independent testing shows 84% efficiency for this power supply at this load level, so component power consumption was closer to 900 W.

AMD’s thermal junction appears to be miscalibrated for this generation of CPU core, consistently reporting temperatures below ambient. Anyone who thinks they can make the corrections will want the raw data (15° and 31° Celsius at stock speeds [idle and load], 19° and 42° overclocked, at an ambient temperature of 21.6°).

Increased fan speed keeps the GPU cores “cool enough” when overclocked.

The June build was a better overall performer, setting this month’s system up for complete failure in an efficiency calculation.

Because overclocking increased performance to a greater degree than power consumption, both systems had higher full-load efficiency when pushed to the limit. Unfortunately, the new system faired far worse at its best efficiency settings than the previous system at its worst.

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