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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  • jeremyshaw - Tuesday, September 22, 2020 - link

    Given how fast the TLC was when the SLC cache was exhausted (and was undoubtedly working on flushing the SLC cache into TLC), I wonder how much faster the native TLC mode of the SSD could be? Reply
  • Billy Tallis - Tuesday, September 22, 2020 - link

    Their ISSCC 2019 presentation about the 512Gbit 128L die (which will be used in the 2TB 980 PRO) claims a write speed of 82MB/s per die. The 1TB 980 PRO is using a total of 32 of the 256Gbit dies, and if it's the same speed then that would work out to 2624 MB/s. So that suggests the total drive fill process is barely slowed down at all by the SLC caching dance, and a datacenter drive using this NAND and controller could hit almost twice the write throughput the current 960GB 983 DCT is rated for. Reply
  • System75 - Wednesday, September 23, 2020 - link

    Why don't you test a fully filled SSD performance anymore like you used to in AnandTech Storage Bench - Heavy? An empty 980 pro drive performance is not what its target consumer wants to know. Reply
  • alyarb - Tuesday, September 22, 2020 - link

    thanks for the memories Samsung, but I'm out Reply
  • nandnandnand - Tuesday, September 22, 2020 - link

    Is the Spirit of Hope dead? Reply
  • Hyoyeon - Tuesday, September 22, 2020 - link

    That SK Hynix P31 could become my new favorite drive. Reply
  • Hifihedgehog - Tuesday, September 22, 2020 - link

    Not quite. The P31 is an amazing value, but I have yet to find a lower latency drive than a Samsung. The P31 does nip at the heels and even surprises in some tests, but it still falls massively short in many latency-sensitive situations where it is easily outclassed by the 970 EVO Plus and above. You get what you pay for.

    https://www.storagereview.com/review/sk-hynix-gold...

    https://www.storagereview.com/review/sk-hynix-gold...
    Reply
  • lmcd - Tuesday, September 22, 2020 - link

    For laptop usage that latency is not even close to worth it. I'm optimistic the upgrade from a 970 EVO (don't worry, it's primarily for a capacity upgrade) will help my inefficient Ryzen 2700U hold on a bit longer when off the charger. Reply
  • MikeMurphy - Tuesday, September 22, 2020 - link

    The P31 performs admirably and does so while consuming very little power and producing very little heat. It doesn't trounce the Samsung drives in every metric but at that price and power budget it doesn't have to. Reply
  • Samus - Wednesday, September 23, 2020 - link

    If Hynix wanted to crank up the heat and power consumption, there is nothing stopping them operating the controller at a higher frequency to reduce the latency caused by processing overhead.

    But they realize there is no need for this at the moment as they have a product that is class-leading in a class it doesn't even compete in.
    Reply

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