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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  • Luckz - Thursday, September 24, 2020 - link

    At reasonable things like 4K random IOPS, the 1TB P31 seems to crush the 2TB Evo Plus. Reply
  • Notmyusualid - Tuesday, October 6, 2020 - link

    @ Hifi.. - yes totally agree on the latency.

    That is why TODAY I just received my 1TB 970 Pro for my laptop. Even choosing it over the 980's... it was the Avg write latency table that sealed the deal for me. (See ATSB Heavy / Write)

    My Toshiba X5GP 2TB (supposedly enterprise class ssd) is not able to keep up with the huge writes my system endures most days. My write performance drops by about 10x, and when I replay my data, there are clear drop-outs.

    The loss of capacity will be a pain, but I'll push old data to the 2TB, as reads on that disk are normal, and if I need to work on a data set, I'll just have to pull it across to the 970 Pro again.

    My 2c.
    Reply
  • romrunning - Tuesday, September 22, 2020 - link

    What this review has done for me is to whet my appetite for an Optane drive. I'm looking forward to seeing how the new AlderStream Optane drives perform! Reply
  • viktorp - Wednesday, September 23, 2020 - link

    Right here with you. Goodbye Samsung, nice knowing you.
    Will advise all my clients to stay away form Samsung for mission critical storage.
    Wish we had a choice of selecting SLC, MLC, TLC, trading capacity for reliability, if desired.
    Reply
  • _Rain - Wednesday, September 23, 2020 - link

    For the sake of your clients, please advice them to use enterprise drives for mission critical storage.
    Those Qvos, Evos and Pros are just client storage drives and not meant for anything critical.
    and of course you can limit the drives capacity to lesser value in order to gain some spare endurance. For example quote 384GB on 512GB drive will definitely double your endurance.
    Reply
  • FunBunny2 - Wednesday, September 23, 2020 - link

    "please advice them to use enterprise drives for mission critical storage."

    does anyone, besides me of course, remember when STEC made 'the best enterprise' SSD? anybody even know about STEC? or any of the other niche 'enterprise' SSD vendors?
    Reply
  • XabanakFanatik - Tuesday, September 22, 2020 - link

    It's almost like my comment on the previous article about the anandtech bench showing the 970 Pro is still faster due to the move to TLC were accurate.

    On the random, when the 980 beats the 970 pro it's by the smallest margin.

    Samsung has really let the professionals like myself that bought pro series drives exclusively down.

    Not to mention over 2 years later than the 970 Pro and it's marginally faster sometimes outside raw burst sequential read/write.
    Reply
  • Jorgp2 - Tuesday, September 22, 2020 - link

    Don't all GPUs already decompress textures?

    And the consoles only have hardware compression to get the most out of their CPUs, same for their audio hardware, video decoders, and hardware scalers.

    There's plenty of efficient software compression techniques, Windows 10 even added new ones that can be applied at the filesystem level. They have good compression, and very little overhead to decompress in real time.
    Only downside is that it's a windows 10 feature, that means it's half baked. Setting the compression flag is ignored by windows, you have to compress manually every time.
    Reply
  • Ryan Smith - Tuesday, September 22, 2020 - link

    "Don't all GPUs already decompress textures?"

    Traditional lossy texture compression is closer to throwing data out at a fixed ratio than it is compression in the lossless sense. Compressed textures don't get compressed so much as texture units interpolate the missing data on the fly.

    This is opposed to lossless compression, which is closer to ZIP file compression. No data is lost, but it has to be explicitly unpacked/decompressed before it can be used. Certain lossless algorithms work on compressed textures, so games store texture data with lossless compression to further keep the game install sizes down. The trade-off being that all of this data then needs uncompressed before the GPU can work on it, and that is a job traditionally done by the CPU.
    Reply
  • jordanclock - Thursday, September 24, 2020 - link

    This fast of a drive combined with DirectStorage has me very excited for this particular reason. Though, as I understand it, DirectStorage requires the game to explicitly call the API and thus needs to be built into the game, as opposed to a passive boost to every game. Reply

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