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 |
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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 |
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Controller | Silicon Motion SM2262EN | ||||
Firmware | HP EX950: FWR1106C ADATA SX8200 Pro: R0906B |
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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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mapesdhs - Thursday, February 7, 2019 - link
I can't help wondering how some of the old favourites would behave in these comparisons, the 950 EVO/Pro, 960s, etc. Have things really moved on that much?Billy Tallis - Thursday, February 7, 2019 - link
We have at least partial test results in Bench for most of the old drives that aren't worth including in every review: https://www.anandtech.com/bench/product/2219?vs=23...eddieobscurant - Thursday, February 7, 2019 - link
It's not about crystal disk mark score. It's about almost no one of the everyday user, playing games, surfing the web and using microsoft office, will come near your "light" test, let alone "heavy" or "torture".Most of them need high random reads for their computer to feel snappy and responsive, and a big enough a slc cache to accommodate a full bluray of writes.
Billy Tallis - Thursday, February 7, 2019 - link
"Most of them need high random reads for their computer to feel snappy and responsive,"They already have that. Further increases to random read performance won't make the system feel any more responsive during light workloads, as demonstrated by SYSmark. High-end NVMe SSDs are already way past the point of diminishing returns for peak random read speeds, especially for lighter workloads where a few GB of DRAM used by the OS for caching is enough to almost completely decouple storage performance from application responsiveness.
eddieobscurant - Friday, February 8, 2019 - link
So, you're saying that optane doesn't feel more responsive to you, or that the high random reads of optane isn't responsible for feeling more responsive than a high end nvme ssd ?Dark_wizzie - Wednesday, February 6, 2019 - link
Why does perf drop on 2tb model?Dark_wizzie - Thursday, February 7, 2019 - link
For low qd random reads, sorry.Dark_wizzie - Thursday, February 7, 2019 - link
And... serves me right for commenting before finishing the last page of the article. >.>oh well.
GreenReaper - Thursday, February 7, 2019 - link
Grabbed an MX500 500GB at Christmas. It's half the price of those tested here, and uses up a spare SATA. Hardly the fastest SSD in the world, but for most purposes it's hard to tell the difference.mapesdhs - Thursday, February 7, 2019 - link
They do seem to be well priced, though I bagged several barely used 850 Pro 512GB units for about the same cost, people seem to be selling them for silly money these days, grud knows why. The 840 Pro is also still very good, one of the most reliable SATA SSDs ever made.