Comparing Two 1TB NVMe Drives with Same NAND, Same Controller: XPG SX8200 Pro vs HP EX950
by Billy Tallis on February 6, 2019 11:30 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.
| HP EX950 and ADATA SX8200 Pro NVMe Power and Thermal Management Features |
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| Controller | Silicon Motion SM2262EN | ||
| Firmware | HP EX950: FWR1106C ADATA SX8200 Pro: R0906B |
||
| 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 | 75 °C | |
| Critical Temperature | 80 °C | ||
| 1.3 | Host Controlled Thermal Management | Supported | |
| Non-Operational Power State Permissive Mode | Not Supported | ||
The HP EX950 and ADATA SX8200 Pro use different firmware version numbering schemes, but they report identical power and thermal management capabilities. The only change relative to SM2262 drives and the SM2262EN engineering sample we reviewed last year is that the warning temperature threshold has been increased from 70 degrees to 75 degrees. The critical temperature threshold is still 80 degrees. The power state table hasn't changed at all, and still advertises very quick transitions in and out of both sleep states.
| HP EX950 and ADATA SX8200 Pro NVMe Power States |
|||||
| Controller | Silicon Motion SM2262EN | ||||
| Firmware | HP EX950: FWR1106C ADATA SX8200 Pro: R0906B |
||||
| Power State |
Maximum Power |
Active/Idle | Entry Latency |
Exit Latency |
|
| PS 0 | 9.0 W | Active | - | - | |
| PS 1 | 4.6 W | Active | - | - | |
| PS 2 | 3.8 W | Active | - | - | |
| PS 3 | 45 mW | Idle | 2 ms | 2 ms | |
| PS 4 | 4 mW | Idle | 6 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.
The retail SM2262EN drives have fully functional power management, unlike the engineering sample we tested last year. Both the ADATA SX8200 Pro and HP EX950 continue the trend of Silicon Motion-based NVMe drives having excellent power management. The active idle power draw is second best among high-end NVMe drives, behind the Phison E12 controller represented here by the Corsair MP510. The Silicon Motion drives achieve better deep sleep power savings than any other NVMe drives can manage on our desktop testbed.
The downside to the excellent idle power management offered by the SM2262EN controller is that it takes quite a while to wake up—60 to 80 milliseconds, slightly longer than earlier Silicon Motion NVMe controllers, and ten times longer than what the drive's firmware claims. This can hurt responsiveness when the OS chooses to be very aggressive about transitioning the drive into lower power states based on inaccurate information about how quickly the drive can get back to work.
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Mikewind Dale - Wednesday, February 6, 2019 - link
That drop in performance for a full drive in the Heavy - and even the Light!! - tests is worrying. They're right around the level of a SATA SSD.My question is, how full is full? If you fill the drive up 99%, is its performance closer to empty or full? With all my SSDs, I typically leave about 10% of the drive unallocated (unpartitioned). How would the drive perform in this state?
I would be interested in seeing results for a drive that is almost full, but not quite full. I imagine that most people don't use their drives up until the final MB is used. Still, if a cost-conscious person is trying to get their money's worth, they might use the drive until it's 90-something percent full. Until recently, I was using a 512 GB SATA SSD with a real capacity of 476.8 GB. I used it until I was using 420 GB, at which point I upgraded to a 2 TB drive. So I was using 88% of its capacity. To me, that seems like a reasonable usage to test - not quite full, but almost full.
Targon - Wednesday, February 6, 2019 - link
I would suspect that the reason for this might be thermal throttle issues. Throw a heat sink on there, and the performance downgrade might disappear. The versions with a pre-installed heatsink might be worth the money, depending on how much it would cost to buy a SSD heatsink at this point(I haven't looked).BillyONeal - Wednesday, February 6, 2019 - link
Seems more likely to be reduction in the size of the SLC cache -- see the the filling the drive tests where there are 3 distinct phases depending on how much space is actually in use.jabber - Thursday, February 7, 2019 - link
I must admit I still leave a few GB spare/unallocated on any SSD I install. 2GB on a 120GB, 4GB on a 240GB and 8GB on a 500GB. Old habits.reactor_au - Thursday, June 13, 2019 - link
I was wondering the same thing, how full can one get before performance drops off the cliff like in the benchmarks? Its a very import detail to omit!Luckz - Friday, November 29, 2019 - link
At 80% full it was really tragic in this review of the 256GB size https://pclab.pl/art79361-9.htmlMikewind Dale - Wednesday, February 6, 2019 - link
I also notice that these drives don't have an active power state less than 3.8W. That's unfortunate, because as Ganesh T S noted in his Anandtech review of the MyDigitalSSD M2X M.2 NVMe SSD Enclosure, that enclosure will only work with SSDs that have an active power state less than 3.8W.I think this is important because it determines whether you can continue to use the SSD as a portable drive after you upgrade later. If you replace your 2 TB with a 4 or 8 TB SSD someday in the future, it will be nice to know that you can repurpose your 2 TB as an external drive.
Also, it determines whether you can easily upgrade your SSD when all your M.2 slots are full. Whenever I upgrade a SATA boot drive, I typically use an external USB enclosure to clone the current SATA drive (still installed internally) to the new SATA drive (inside the enclosure). Then I can swap the two drives, and my computer will transparently use the new drive. With M.2, this is even more important because many motherboards have only two M.2 sockets. So if you have both M.2 sockets filled and try to upgrade one of the M.2 drives, you'll have a bit of a challenge. You could buy a PCIe-M.2 card and use that, but using an external USB enclosure is more convenient.
So I'd like to see more M.2 drives with a sub-3.8 W active power state. The Samsung 970 EVO Plus has a 3.4 W active state, so it passes this test.
MrSpadge - Wednesday, February 6, 2019 - link
I love ADATA's naming scheme! It's so easily memorable and has more X's than any other brand.eddieobscurant - Wednesday, February 6, 2019 - link
Nice review , as always although I disagree with your conclusion. Peak performance is what most people want.Billy Tallis - Wednesday, February 6, 2019 - link
My reviews are intended to advise consumers who are buying SSDs to increase their productivity, not people who are trying to set a high score on Crystal Disk Mark.People who care about real-world productivity rather than CDM scores should recognize that imperceptible improvements to peak performance are probably not worth the sacrifice of significant regressions in performance on niche heavy workloads. For a lot of users, both SM2262 and SM2262EN drives are fast enough. Beyond those lighter use cases, I think it will be more common to find the SM2262EN coming up short in a meaningful way than to find it providing a tangible performance advantage over SM2262.