Results: Power And Heat
Intel's Hyper-Threading simultaneous multi-threading technology doesn’t increase consumption much on its own, but when it increases core utilization through greater parallelism, those cores do use more power. We've seen this in a few benchmarks, and it also shows up in power consumption numbers. There’s no free lunch.
The $600 machine is the true miser, but not because of its 100 W CPU. Rather, the Pitcairn-based R7 265 graphics card appears to be Paul's saving grace based on our load power measurements.
There’s that 80-degree ceiling again. You know it as the temperature where Intel’s Haswell-based cores throttle in a 20° (Celsius) room. But again, I have to point out that this was measured when both the CPU and GPU were fully-loaded, and that I picked a graphics card that vents all of its waste heat (and there's a lot) internally and put it in a case with one exhaust fan.
Then again, the same can be said of Don’s no-so-hot graphics card. Combining a lower overclocked CPU voltage and GPU wattage are a huge benefit to his temperatures under load.
AMD's processor behave a little differently, traditionally running into stability issues when the CPU hits mid-60s. So, Paul's $600 machine probably falls between the other two builds in terms of environmental heat tolerance. This is where I ask Paul to stop his fan and see if the system crashes.