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Power Consumption And Efficiency

AMD FX-8350 Review: Does Piledriver Fix Bulldozer's Flaws?
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It’s always interesting to do a full analysis of performance before taking a look at the power consumption log files I generate while the benchmarks run.

It's a little unexpected to see the Piledriver-based FX-8350 (the blue line) clearly using less power over the course of our benchmark suite than the Bulldozer-based FX-8150 (the green line), even though the previous-gen part operates at a base frequency 400 MHz lower.

Before I get into the specifics, I want to point out a small change I’m making in this review. Normally, I cut the power log off as soon as the last test finishes. This fails to account for idle power use, though, as the script is constantly starting and stopping benchmarks. Today, I’m giving each system exactly 600 seconds (10 minutes) to idle at the end of the run. As a result, average power use is brought down and energy consumption increases (due to the longer measurement period), but we do get a more realistic look at how these systems do when they’re allowed to rest.

I don’t have a chart for each machine’s idle power consumption. Looking over each log, however, tells us that the Core i5 and Core i7 idle the lowest (roughly 79 and 80 W, respectively). The Phenom II X6-based system pulls about 102 W from the wall when it’s not doing anything. And the machine with an FX-8150 draws 92 W. FX-8350 fares no better, idling at 92 W as well. But it finishes the whole suite so much faster that efficiency almost certainly improves.

Average power consumption and the time taken to finish all of our benchmarks will shed some light on Vishera’s efficiency. 

Across our benchmark suite, the FX-8350-based system used 10 W less than the same machine with FX-8150, despite its higher clock rate and better performance.

We have a pretty good idea that the FX-8350 is quicker than AMD’s old Phenom II X6 1100T. But the six-core chip’s lower power consumption could translate to better efficiency if it isn’t significantly slower. That’d be a disaster for AMD.

The fact that both chips from Intel average dramatically lower power use across the run makes it almost impossible for the Piledriver-based Vishera platform to catch up.

This is something for AMD to be proud of. Its FX-8350 finishes in second place (of the CPUs I charted—I tried to pick and choose carefully to keep the graph from getting too hectic). For the record, though, I also had to know how FX-8350 did against Core i5-3570K, and it finished 12 seconds before the pricier Intel chip.

Even though it wraps up the total workload less than 10 minutes sooner than the FX-8150, the fact that AMD is charging less than $200 for its desktop flagship completely changes the processor’s value proposition. How efficient is it, though?

FX-8350 is almost 13% more efficient than its predecessor. Perhaps more important, it proves to be more efficient than Phenom II X6 1100T.

One year ago, the Phenom was a more power-friendly choice than the Bulldozer-based FX. There was no way to escape the fact that AMD had put out a CPU that used more power and performed worse in a number of key applications. Now we’re at least able to acknowledge better performance, better efficiency, and a more attractive price. Is all of that enough to garner a recommendation?

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