Trying to choose a low power draw M.2 SSD for mobile use, but power data is inconsistent?

Question

I'm going to be using an M.2 SSD via USB3 in place of a USB flash stick, for my notebook. The main "heavy" use will be at home or work, to load it up or unload it with files, and in those places, the host PC/device is mains powered so power isn't an issue. The purpose of upgrading is to be able to load up and offload files much faster than with usual USB sticks, if I'm in a rush.

But I will also somewhat use the device and the files on it while travelling - to watch a movie on a train, or to work on documents. In those cases it's using host power, and low power draw will mean a longer battery life which is important.

The trouble is, that information in benchmarks and data websites is conflicting on the power draw in use. So I'm not sure which devices to consider. For example, product info/market trawler skinflint.co.uk states that the Intel 540s has a tiny fraction of the in-use power of the Samsung 850 EVO (0.08W vs 3.5W), whereas Anandtech says they are about the same (1.22W vs. 1.31W) - and 15x more/3x less than the other figures respectively.

The files are a mix of sizes (4k/100k/1gb) so decent 4k performance will be needed, but I can get that from stats and tests as usual.

It's the power in use data that I don't understand, because I wouldn't expect a company like Intel to advertise 0.08 if a realistic figure was 1.31 - that's too large a gap for marketing to swallow and they are usually fairly reliable in their product data.

I'd like to understand the difference in the above numbers, and what data I should use/trust, as it's so striking.

Answer 1

You have to remember that "low" data rate things like watching a film will leave the drive in the idle state a significant majority of the time.

For example 20-30Mb/s video will use approx 5MB/s of the drive's 550MB/s+ capability... or to put it another way less than 1%.

So you are not really interested in the "in use" figures for this "watching a film on the train" use-case... you are much more interested in the idle power figures.

In addition to this, do not forget the power consumption of the USB controller.

---

To address your concern regarding the discrepancy between AnandTech's measured and Intel's reported power usage, I would question the method that AnandTech are using to get their figures - they didn't mention it in the report as far as I could see.