Power Consumption Benchmarks
To test power usage, we removed the power-hungry Radeon HD 4890 and ran the system using the integrated 785G graphics processor.
We did experience an interesting phenomenon: the system would crash when the C1E power saving feature was enabled in the BIOS (this is something we believed was being enabled in hardware now on AMD CPUs), so we had to leave that option disabled. We contacted Asus about this issue to see if it is a problem with our test sample or if it can be repaired with a BIOS update. Regardless, power usage remained very low.
We did notice that when we enabled the memory power down feature of the motherboard, we saved about six watts both under load and at idle. We were a little surprised at the consistency and quantity of savings with this feature. All of the power consumption benchmarks were taken with the Cool'n'Quiet and memory power down features enabled.
Note that we start the chart at 40W. We generally try to start our charts at zero, but in this case the rest of the system is probably drawing about 40W aside from the CPU. Our goal is to isolate the CPU usage.
Our first thought is that the Athlon II X2 250 is surprisingly frugal for a 3.0 GHz part, coming within a couple watts of its low-power derivative, the 240e. All of the cache on the Phenom II models seem to up the ante, and more CPU cores also require more power.
The new Athlon II X3 435 requires less juice than its quad-core Athlon II X4 620 cousin, but it also delivers better performance in apps and games that depend on clock speed as well as multi-threading, making it a well-rounded CPU.
Overclocking is another story entirely, with load power of the overclocked Athlon II X3 435 consuming more than its brethren. Idling is where most PCs spend their time however, and in this respect the overclocked Athlon II X3 435 draws only 16 more watts than its stock clock speed.
2 cores 2 threads?
Aha! Thanks for catching that. After I had done the testing I was playing around with disabling CPU cores in the OS, and I forgot to turn them back on to take the screenshot. Fixed!