Power consumption and efficiency
The workload for this test is encoding a video with x264, based on a command ripped straight from the x264 benchmark you'll see later.
Lower TDP or not, the FX-8370E doesn't draw any less power than its 125W cousins at idle. The Core i5-4590 consumes 19W less here.
Fire up a video-encoding workload, and the FX-8370E shines compared to its relatives. While its TDP is only 30W lower than the FX-8370's on paper, the FX-8370E actually draws almost 50W less in this test. Too bad that difference isn't enough to close the gap with the Core i5-4590.
We can quantify efficiency by looking at the amount of power used, in kilojoules, during the entirety of our test period, when the chips are busy and at idle.
Perhaps our best measure of CPU power efficiency is task energy: the amount of energy used while encoding our video. This measure rewards CPUs for finishing the job sooner, but it doesn't account for power draw at idle.
As we'll see in our performance section, the FX chips chew through this x264 test quite a bit slower than the Intel ones. That means the AMD CPUs spend more time at peak power draw, which compounds the effect of their already-high power consumption. No wonder they're stuck at the bottom of the graph. The FX-8370E isn't the worst of the bunch, but it's still much less efficient than the Core i5-4590.