The SSD Power Consumption Hoax

Flash SSDs Don’t Improve Your Notebook Battery Runtime – they Reduce It

Flash-based solid state drives (SSDs) are considered to be the future of performance hard drives, and everyone seems to be jumping on the bandwagon. We are no exception, as we have been publishing many articles on flash-based SSDs during the last few months, emphasizing the performance gains and the potential power savings brought by flash memory. And there is nothing wrong with this, since SLC flash SSDs easily outperform conventional hard drives today (SLC = single level cell). However, we have discovered that the power savings aren’t there: in fact, battery runtimes actually decrease if you use a flash SSD.

Could Tom’s Hardware be Wrong?

No, our results are definitely correct. We’ve looked at almost a dozen different flash SSDs from seven vendors over the last few months, and measured acceptable or sometimes even disappointing power requirements with most flash SSDs. In an effort to determine the actual impact on notebook systems, we took four SSDs that we had available in our test lab, and ran a series of Mobilemark benchmark runs on a Dell Latitude D630 notebook. We found runtime differences of up to one hour (!) when using a flash SSD compared to a high-performance 7,200 RPM 2.5” notebook hard drive.

Will this Slow Down the Flash Memory Hype?

We don’t think so. Flash is cool, because it’s expensive, and because it does provide significant performance advantages (when SLC flash is used). But while our results are interesting for most users, they will be shocking to road warriors. You will see very clearly in the benchmark section that theory and real life are sometimes entirely different.

We still believe that flash-based drives will be the future for the performance segment, but they must not become a key component for energy-efficient notebooks and ultra-portables — where performance is secondary — as long as their average power consumption is higher than that of conventional 2.5” notebook hard drives. In fact, even a high-performance 7,200 RPM 2.5” drive provided better overall battery runtime than most of the flash SSDs we put through the Mobilemark test.

Update: We apologize for a procedural mistake in testing battery runtime for this article. As the benchmark looped, the total workload processed by the fast Flash SSDs was higher, causing other components, such as the chipset and the CPU, to be more active as well. We followed up with the article Flash SSD Update: More Results, More Answers, which proves our conclusion correct, despite the procedural mistake. Most of the Flash SSDs are not there yet. However, OCZ’s SATA-II Flash SSD proves that the technology has the potential to leave hard drives in the dust.