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.
Active idle power numbers are critical, especially when it comes to their impact on mobile platforms. Idle means different things on different systems, though. Pretty much every drive we're testing is capable of one or more low-power states, up to and including DevSleep. DevSleep is a part of the SATA 3.2 host specification, and while it requires a capable SSD and a compatible platform, enabling it takes storage down to very little power use. This is why we test active idle; it's easy to identify and is still where SSDs spend most of their time.
The A110 poses special issues where power consumption testing is concerned, since its PCIe nature makes it difficult to measure. Fortunately, the x4 PCIe-to-M.2 PCIe adapter we have lets us power the drive using external power, via four-pin Molex connector. That makes taking a reading easier, though we're not certain yet whether the accuracy is affected.
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" between peaks of varying intensity.
The A110 spends most of its time at the idle power state we measured, but increases from there. The spikes are super-short though, telling us that SanDisk's drive does what it's asked and then drops back to idle quickly. PCMark 7 doesn't tax the A110 much at all.
In fact, the A110 uses just slightly more power, on average, in this workload than it did in our idle measurement. As a result, it moves up this chart.
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.
No matter what tortuous workload we threw at it, the 256 GB A110 wouldn't use more than 3.5 W. SanDisk rates the drive for up to 5.5 W in write tasks, but we were unable to approach that figure.
- SanDisk A110 256 GB: Introducing The M.2 SSD Form Factor
- More On M.2 And SanDisk's Fancy PCIe Adapter Card
- Results: Sequential Performance
- Results: Random Performance
- Results: Tom's Hardware Storage Bench v1.0
- Results: Tom's Hardware Storage Bench v1.0, Continued
- Results: PCMark 7 And PCMark Vantage
- Results: File Copy Performance
- Results: Power Consumption
- PCI Express-Attached M.2: Ready For Prime Time