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Power And Heat

System Builder Marathon, May '09: $2,500 Performance PC

We continue to use multiple threads of Prime95 to gauge peak CPU power consumption, but have switched to FurMark for 3D heat and power testing. Because FurMark needs a CPU core of its own to run at full speed, we disabled Prime95 threads 1 and 2 for the combined CPU and GPU power test.

Putting aside any concerns about environmental impact, anyone who cares even slightly about their power bill might be shocked to see that every hour of high-end gaming adds a full kilowatt hour to their power bill (much more if the room is air conditioned).

Here we see the problem with overclocked dual-GPU graphics units. An experiment showed that forcing cool air into our system allowed an additional 10% increase in stable graphics system clocks, but we didn’t use any such cheats for today’s tests.

CPU heat was less significant only because we used a low-core voltage. A better sink from the Core i7 Extreme Edition 965 would have allowed the more expensive processor to run at higher clock speeds, but what our system really needed was a higher-speed CPU fan. We’re not certain why Intel would limit its fan to a maximum of 2,100 RPM when automatic speed controls would have allowed a 3,000 RPM fan to produce similar noise levels in “typical environments” and it’s unfortunate that high-performance CPU coolers will not fit within the confines of this system.

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