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, 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 relevant. 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.
Interestingly, the M500s demonstrate high idle power consumption. That's an important result for mobile users who may be inclined to swap drives and don't want to see their battery life suffer. Of course, with the implementation of device- and host-initiated power management, plus deeper sleep states in Intel's Haswell architecture, the significance of these numbers may be mitigated somewhat.
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. You can see the drives fall back down to the idle "floor", interspersed with peaks of varying intensity.
All four drives idle around the same wattage, so you mostly see them hanging out at a similar level. Then, when PCMark 7 ramps up its tests, we get spikes corresponding to heavier use, especially those triggered by writes to each drive. Maximum power consumption varies by capacity, so you don't even need the graphics legend to tell the four M500s apart.
The squadron of M500s follows the same pattern as most other drives, registering slightly more power consumption than the idle result during a complete run of the PCMark storage suite. Crucial's entire line-up does end up in the bottom half of this chart, though the results aren't bad considering how power scales up from idle. On average, the increase is only a few more milliwatts.
Maximum Observed Power Consumption
It's even better news that maximum power consumption isn't a critical specification for most desktop workloads. In the enterprise space, yes. This information goes into the calculation for total cost of ownership. But in a client environment, you shouldn't be seeing these numbers for more than short bursts.
It's safe to say that 1 TB of flash is a lot for one drive, and we don't find it unusual that the large 960 GB model uses the most power in Crucial's M500 line-up. Frankly, 5.3 W is a reasonable number for such a high-capacity SSD.
But Samsung's 1 TB 840 EVO places quite a bit more favorably, despite its use of three-bit-per-cell flash.