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.

Samsung 980 PRO
NVMe Power and Thermal Management Features
Controller Samsung Elpis
Firmware 1B2QGXA7
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 82°C
Critical Temperature 85°C
1.3 Host Controlled Thermal Management Supported
 Non-Operational Power State Permissive Mode Not Supported

The set of power management features supported by the 980 PRO is the same as what the 970 generation offered. The active state power levels have been tweaked and the highest power state can now reach 8.49W: definitely high for a M.2 drive, but not as problematic as the 10.73W declared by the Phison E16-based Seagate FireCuda 520. Power state transition latencies for the 980 PRO have also been adjusted slightly, but the overall picture is still a promise of very quick state changes.

Samsung 980 PRO
NVMe Power States
Controller Samsung Elpis
Firmware 1B2QGXA7
Power
State
Maximum
Power
Active/Idle Entry
Latency
Exit
Latency
PS 0 8.49 W Active - -
PS 1 4.48 W Active - 0.2 ms
PS 2 3.18 W Active - 1.0 ms
PS 3 40 mW Idle 2.0 ms 1.2 ms
PS 4 5 mW Idle 0.5 ms 9.5 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, and depending on which NVMe driver is in use. Additionally, there are multiple degrees of PCIe link power savings possible through Active State Power Management (APSM).

We report three idle power measurements. Active idle is representative of a typical desktop, where none of the advanced PCIe link power saving features are enabled and the drive is immediately ready to process new commands. Our Desktop Idle number represents what can usually be expected from a desktop system that is configured to enable SATA link power management, PCIe ASPM and NVMe APST, but where the lowest PCIe L1.2 link power states are not available. The Laptop Idle number represents the maximum power savings possible with all the NVMe and PCIe power management features in use—usually the default for a battery-powered system but rarely achievable on a desktop even after changing BIOS and OS settings. Since we don't have a way to enable SATA DevSleep on any of our testbeds, SATA drives are omitted from the Laptop Idle charts.

 

We haven't sorted out all the power management quirks (or, less politely: bugs) on our new Ryzen testbed, so the idle power results below are mostly from our Coffee Lake system. The PCIe Gen4 drives have been tested on both systems, but for now we are unable to use the lowest-power idle states on the Ryzen system.

Since AMD has not enabled PCIe 4 on their Renoir mobile platform and Intel's Tiger Lake isn't quite shipping yet, these scores are still fairly representative of how these Gen4-capable drives handle power management in a typical mobile setting. Once we're able to get PCIe power management fully working crash-free on our Ryzen testbed, we'll update these scores in our Bench database.

Idle Power Consumption - No PMIdle Power Consumption - DesktopIdle Power Consumption - Laptop

The active idle power draw from the 980 PRO unsurprisingly differs quite a bit depending on whether it's running the PCIe link at Gen3 or Gen4 speeds. At Gen3 speeds, the active idle power is decently low for an 8-channel controller and is an improvement over the 970 generation. At Gen4 speeds the active idle power is a bit on the high side of normal, but still lower than the Phison E16 and the WD Black that is something of an outlier.

The desktop idle power draw for the 980 PROs is less than half what we saw with the Samsung 970 generation drives, but not quite as low as the Silicon Motion SM2262EN achieves. On our Coffee Lake system, the 980 PROs are both able to achieve single digit milliwatt idle power.

Idle Wake-Up Latency

The idle wake-up times for the 980 PROs are all very quick, though waking up from the desktop idle state to Gen4 speed does seem to take longer than reestablishing a Gen3 link. Some of the previous-generation Samsung drives we tested exhibited wake-up latencies of several milliseconds, but so far the 980 PRO doesn't seem to do that and aggressively using the deepest idle states achievable won't noticeably hurt system responsiveness.

Mixed Read/Write Performance Conclusion: Top Shelf, No Drama
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  • romrunning - Tuesday, September 22, 2020 - link

    Agreed! Reply
  • Tomatotech - Wednesday, September 23, 2020 - link

    See the StoragePro review for some eyebrow-raising numbers that may change your view.

    https://www.storagereview.com/review/samsung-980-p...
    Reply
  • Tams80 - Tuesday, September 22, 2020 - link

    What's the point of these if they are going to use TLC? They already make TLC SSDs and the market is pretty full.

    So what if using MLC is more expensive? Isn't the whole point of these to be their best of the best? And if an SLC cache benefits TLC SSDs, then why not have an MLC SSD with an SLC cache?
    Reply
  • Kaziglu Bey - Tuesday, September 22, 2020 - link

    Not the hope we're looking for.
    Time for me to buy another 2TB SX8200 Pro.
    Reply
  • vladx - Thursday, September 24, 2020 - link

    Yep, beyond enterprise workloads there's no point buying anything other than the SSD with best price/GB. Reply
  • Makaveli - Tuesday, September 22, 2020 - link

    What were they thinking here.

    600 TBW on this "Pro" drive then a small 114GB SLC cache?

    The E16 offers 1,800 TBW at 1TB and 333GB SLC cache.

    Not impressed with this drive and looking forward to the E18 drives that are slowly coming out.
    Reply
  • Luckz - Thursday, September 24, 2020 - link

    You mean it will just use the entire empty SSD, because leaving the SSD empty is both a 'feature' and a smart use case? I barely even have 10% free on actively used SSDs. Reply
  • Golgatha777 - Tuesday, September 22, 2020 - link

    For $20 more, I'll take a slight performance hit, but gain 4X the endurance by buying a 512GB 970 Pro. There's been nothing worth upgrading to since the 950 Pro when it comes to real world usage anyway though. Reply
  • MDD1963 - Tuesday, September 22, 2020 - link

    I've written 30 TB in 3 years to my 960 EVO...; folks worried about 'only' 600 TBW (60 years at my rate usage?) specs are amusing. Reply
  • Makaveli - Tuesday, September 22, 2020 - link

    And its assuming to me that you think your anecdotal point speaks for the whole market. Reply

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