Power Management Features

Real-world client storage workloads leave SSDs idle most of the time, so the active power measurements presented earlier in this review only account for a small part of what determines a drive's suitability for battery-powered use. Especially under light use, the power efficiency of a SSD is determined mostly be how well it can save power when idle.

For many NVMe SSDs, the closely related matter of thermal management can also be important. M.2 SSDs can concentrate a lot of power in a very small space. They may also be used in locations with high ambient temperatures and poor cooling, such as tucked under a GPU on a desktop motherboard, or in a poorly-ventilated notebook.

Intel SSD 660p 1TB
NVMe Power and Thermal Management Features
Controller Silicon Motion SM2263
Firmware NHF034C
NVMe
Version
Feature Status
1.0 Number of operational (active) power states 3
1.1 Number of non-operational (idle) power states 2
Autonomous Power State Transition (APST) Supported
1.2 Warning Temperature 77°C
Critical Temperature 80°C
1.3 Host Controlled Thermal Management Supported
 Non-Operational Power State Permissive Mode Not Supported

The Intel SSD 660p's power and thermal management feature set is typical for current-generation NVMe SSDs. The rated exit latency from the deepest idle power state is quite a bit faster than what we have measured in practice from this generation of Silicon Motion controllers, but otherwise the drive's claims about its idle states seem realistic.

Intel SSD 660p 1TB
NVMe Power States
Controller Silicon Motion SM2263
Firmware NHF034C
Power
State
Maximum
Power
Active/Idle Entry
Latency
Exit
Latency
PS 0 4.0 W Active - -
PS 1 3.0 W Active - -
PS 2 2.2 W Active - -
PS 3 30 mW Idle 5 ms 5 ms
PS 4 4 mW Idle 5 ms 9 ms

Note that the above tables reflect only the information provided by the drive to the OS. The power and latency numbers are often very conservative estimates, but they are what the OS uses to determine which idle states to use and how long to wait before dropping to a deeper idle state.

Idle Power Measurement

SATA SSDs are tested with SATA link power management disabled to measure their active idle power draw, and with it enabled for the deeper idle power consumption score and the idle wake-up latency test. Our testbed, like any ordinary desktop system, cannot trigger the deepest DevSleep idle state.

Idle power management for NVMe SSDs is far more complicated than for SATA SSDs. NVMe SSDs can support several different idle power states, and through the Autonomous Power State Transition (APST) feature the operating system can set a drive's policy for when to drop down to a lower power state. There is typically a tradeoff in that lower-power states take longer to enter and wake up from, so the choice about what power states to use may differ for desktop and notebooks.

We report two idle power measurements. Active idle is representative of a typical desktop, where none of the advanced PCIe link or NVMe power saving features are enabled and the drive is immediately ready to process new commands. The idle power consumption metric is measured with PCIe Active State Power Management L1.2 state enabled and NVMe APST enabled if supported.

Active Idle Power Consumption (No LPM)Idle Power Consumption

The Intel 660p has a slightly lower active idle power draw than the SM2262-based drives we've tested, thanks to the smaller controller and reduced DRAM capacity. It isn't the lowest active idle power we've measured from a NVMe SSD, but it is definitely better than most high-end NVMe drives. In the deepest idle state our desktop testbed can use, we measure an excellent 10mW draw.

Idle Wake-Up Latency

The Intel 660p's idle wake-up time of about 55ms is typical for Silicon Motion's current generation of controllers and much better than their first-generation NVMe controller as used in the Intel SSD 600p. The Phison E12 can wake up in under 2ms from a sleep state of about 52mW, but otherwise the NVMe SSDs that wake up quickly were saving far less power than the 660p's deep idle.

Mixed Read/Write Performance Conclusion
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  • Spunjji - Wednesday, August 8, 2018 - link

    It was pretty obvious that the 840 was affected because it used the same NAND as the 840 Evo, just without the caching mode. It was also pretty obvious that Samsung didn't care because it was "old" so they never properly fixed it. Reply
  • OwCH - Wednesday, August 8, 2018 - link

    Ryan, I love that you will. It is not easy for the user to find real world data on these things and it is, at least to me, information that I want before making the decision to buy a drive.

    Looking forward to it!

    Thanks!
    Reply
  • Solid State Brain - Tuesday, August 7, 2018 - link

    The stated write endurance should already factor data retention, if it follows JEDEC specifications (JESD219A). For consumer drives, it should be be when the retention time for freshly stored data drops below 1 year after the SSD is powered off, at 30°C. Reply
  • BurntMyBacon - Wednesday, August 8, 2018 - link

    The Samsung 840 EVO would like to have a word with you. Reply
  • eastcoast_pete - Wednesday, August 8, 2018 - link

    Yes, it should factor data retention, and it should follow JEDEC specs. The problem is the "should". That doesn't mean it or they do. I found that "Trust but verify" is as important in IT as it is in life. Even the biggest names screw up, at least occasionally. Reply
  • IntenvidiAMD - Tuesday, August 7, 2018 - link

    Are there any reviewers that do test that? Reply
  • DanNeely - Tuesday, August 7, 2018 - link

    Over 18 months between 2013 and 2015 Tech Report tortured a set of early generation SSDs to death via continuous writing until they failed. I'm not aware of anyone else doing the same more recently. Power off retention testing is probably beyond anyone without major OEM sponsorship because each time you power a drive on to see if it's still good you've given its firmware a chance to start running a refresh cycle if needed. As a result to look beyond really short time spans, you'd need an entire stack of each model of drive tested.

    https://techreport.com/review/27909/the-ssd-endura...
    Reply
  • Oxford Guy - Tuesday, August 7, 2018 - link

    Torture tests don't test voltage fading from disuse, though. Reply
  • StrangerGuy - Tuesday, August 7, 2018 - link

    And audiophiles always claim no tests are ever enough to disprove their supernatural hearing claims, so... Reply
  • Oxford Guy - Tuesday, August 7, 2018 - link

    SSD defects have been found in a variety of models, such as the 840 and the OCZ Vertex 2. Reply

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