The Mainstream Phoenix Rises: Samsung's 970 EVO (500GB & 1TB) SSDs Reviewed
by Billy Tallis on April 24, 2018 10:00 AM ESTPower 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 970 EVO NVMe Power and Thermal Management Features |
|||
| Controller | Samsung Phoenix | ||
| Firmware | 1B2QEXE7 | ||
| 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 | 85°C | |
| Critical Temperature | 85°C | ||
| 1.3 | Host Controlled Thermal Management | Supported | |
| Non-Operational Power State Permissive Mode | Not Supported | ||
The Samsung 970 EVO bumps the supported NVMe spec version to 1.3, compared to the 1.2 feature set supported by the PM981 and 960 series. The 970 EVO implements the Host Controlled Thermal Management feature, allowing operating systems to configure the drive to throttle at a lower temperature than it normally would. The (optional) non-operational power state permissive mode feature is not included, so the 970 EVO is not supposed to do background tasks like garbage collection when it is in idle power states (unless they can be done within the power constraints of the idle states, which is unrealistic).
| Samsung 970 EVO NVMe Power States |
|||||
| Controller | Samsung Phoenix | ||||
| Firmware | 1B2QEXE7 | ||||
| Power State |
Maximum Power |
Active/Idle | Entry Latency |
Exit Latency |
|
| PS 0 | 6.2 W | Active | - | - | |
| PS 1 | 4.3 W | Active | - | - | |
| PS 2 | 2.1 W | Active | - | - | |
| PS 3 | 0.04 W | Idle | 0.21 ms | 1.2 ms | |
| PS 4 | 0.005 W | Idle | 2 ms | 8 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 draw of the 970 EVO seems to be about 20% higher than the preceding generation of Samsung drives, but the low-power idle we measured is about the same as most other high-end NVMe drives.
The idle wake-up latency of the 970 EVO is more than twice that of its predecessors and also significantly higher than that of the Samsung PM981. This ~14ms latency exceeds the 8ms that the drive itself claims as its latency to wake up from its deepest sleep state.
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bji - Tuesday, April 24, 2018 - link
You're kind of arguing against benchmarking in general here. Almost no benchmarks are directly relevant to any one person's intended use of the product. Benchmarks are not useful in that they tell me exactly how much performance to expect when running one specific program on one specifically configured hardware setup. They are useful because they allow extrapolation from measured results to expected results on workloads that actually matter to the reader.So I don't agree with your sentiment that Meltdown/Spectre are not worth consideration for their effect on system performance.
However, I am not sure that I would include Meltdown/Spectre considerations in a specific SSD review. I think these considerations deserve to be in a CPU review.
bji - Tuesday, April 24, 2018 - link
Also, may I say that users generally will not notice a 5% slowdown in any particular task; however, we've already established that readers care about minimum differences in benchmark results, because they routinely call a 5% difference clear indication of a "winner" and a "loser" for that benchmark, so for the purposes of performance reviews, the 5% difference contributed by Meltdown/Spectre definitely matters.Flying Aardvark - Tuesday, April 24, 2018 - link
It's up to 50% reduction in storage performance not 5%. You'll feel 50% loss when it happens to you.cmdrdredd - Tuesday, April 24, 2018 - link
What you are saying is misleading. SATA performance is nearly identical (within 2% difference for me). It's NVMe drives that take the hit, but even still they are faster than everything else. Processor speed is unaffected for me as well. Tested multiple times with various benchmarks both ways and it was within margin of error. I don't see the problem to be honest.LurkingSince97 - Wednesday, April 25, 2018 - link
Tell that to my I/O intensive servers that suddenly have 30% less throughput.modeonoff - Tuesday, April 24, 2018 - link
Yes but I am not an average customer. Performance is important for me.Ryun - Tuesday, April 24, 2018 - link
For everyday tasks do you guys notice an improvement in responsiveness of NVMe SSDs versus SATA SSDs?The transfer rates are definitely impressive, I've just never seen a review where I've wanted to upgrade my 500GB SATA SSD for development/gaming/maintenance tasks on my machine. Seems like boot times and opening programs are within a couple seconds of another between NVMe and SATA. Nothing like the jump between HDDs vs SSDs.
HollyDOL - Tuesday, April 24, 2018 - link
I wonder myself, got Vertex 3 (240GB) and while not permanently watching perf counters I don't see much cases of 100% load. Wonder if I would be able to see a difference if I moved to some "best enthusiast m.2/pcie ssd available". (Rest of the machine is fully capable)eek2121 - Tuesday, April 24, 2018 - link
I notice it in certain tasks. My system can get from cold boot to the login screen in about 3 seconds for instance. Editing video is much faster as well.imaheadcase - Tuesday, April 24, 2018 - link
I wouldnt say a huge performance, it really depends on certain tasks that you work with. If you work with file manager a lot with big files sure. But most people no. It makes sense if just upgrading though.