Results: Power Consumption
Idle Power Consumption
Idle consumption is the most important power metric for consumer and client SSDs. After all, solid-state drives complete host commands quickly, and then drop back down to idle. Aside from the occasional background garbage collection and house keeping, a modern SSD spends most of its life doing very little. Enterprise-oriented drives are more frequently used at full tilt, making their idle power numbers far less important. But this just isn't the case on the desktop, where the demands of client and consumer computing leave most SSDs sitting on their hands for long stretches of time.
The EVO's MEX controller pulls active idle consumption even lower, dropping to under one third of a watt.
PCMark 7 Average Power Consumption
If we log power consumption through a workload, even a relatively heavy one, we see that average use is still pretty close to the idle numbers. Max power may spike fiercely, but the usage seen during a PCMark 7 run is pretty light.
During the run, each tested drive drops from peak to idle over and over again. Often, those peaks correspond to drive capacity; the more flash in a given SSD, the higher we see power consumption reach.
Averaging out power use during a PCMark run can give us a more accurate look at what a moderate desktop workload looks like with regard to power. Again, we observed higher-capacity drives consuming more power during a run, while smaller SSDs rise to the top.
Maximum Observed Power Consumption
There isn't much to say about maximum observed power consumption. It doesn't warrant a lot of explanation, aside from the fact that few client workloads trigger these levels of use. It's a much more important metric in enterprise applications, where maximum consumption is a critical variable in total cost of ownership.
Periods of high power use happen occasionally, but only briefly. Idle power figures are more representative when it comes to picking an SSD that's going to help extend your notebook's battery life, though maximum numbers that reach too high are worrisome as well.
The 840 EVO has a throttling mechanism to keep temperatures and drive health in check during the most taxing, heat-intensive situations, though we wouldn't recommend testing those boundaries.