Internals, Testing Methodology and System Setup
Internals:
Not much to take apart here, but I'll do what I can:
With the stickers removed, we can see the controllers and flash. The XP841 (top) and AHCI SM951 (bottom) have similar component counts (when you consider components mounted on the top and bottom of the PCB), save two additional flash packages on the 512GB unit. The center position is held by the NVMe version of the SM951, which fits all components neatly onto the front side of the PCB.
NVMe
To summarize what we detailed back in the P3700 article, NVMe is a new protocol that replaces the dated AHCI stack. Similar to how Directx 12 reduces CPU overhead for graphics calls, NVMe reduces CPU overhead for storage IO calls. This is necessary in order to get SSD performance past the limits of the older protocol. Without it, SSDs capable of high IOPS would also require many CPU cores fully saturated to support them. NVMe eases that bottleneck, along with some great bonuses in the form of reduced latency oer IO.
Testing Methodology
Our tests are a mix of synthetic and real-world benchmarks. IOMeter, HDTach, HDTune, Yapt and our custom File Copy test round out the selection to cover just about all bases. If you have any questions about our tests just drop into the Storage Forum and we'll help you out!
Test System Setup
We have several storage testbeds. A newer ASUS P8Z77-V Pro/Thunderbolt and an ASUS Z87-PRO. Variance between both boards has been deemed negligible when testing SATA devices. Future PCIe and SATA device testing, including this review, will take place on a new ASUS Sabertooth X99, which comes equipped with USB 3.1, M.2, and can also handle SFF-8639 devices with the proper adapter.
PC Perspective would like to thank Intel, ASUS, Corsair, Kingston, and EVGA for supplying some of the components of our test rigs.
| Hard Drive Test System Setup | |
| CPU | Intel Core i7 5820K @ 4.125 GHz |
| Motherboard | ASUS Sabertooth X99 |
| Memory | 16GB Micron DDR4 @ 3333 |
| Hard Drive | G.Skill 32GB SLC SSD |
| Sound Card | N/A |
| Video Card | EVGA GeForce GTX 750 |
| Video Drivers | GeForce Game Ready Driver 347.88 |
| Power Supply | Corsair CMPSU-650TX |
| DirectX Version | N/A |
| Operating System | Windows 8.1 Pro X64 (update) |
- PCPer File Copy Test
- HDTach
- HDTune
- IOMeter
- YAPT
Hey Allyn,
I approach most of
Hey Allyn,
I approach most of this from a gamer’s perspective. Of course, I wouldn’t expect night and day difference with a very high end SSD vs a normal SSD. But what about for something like running around Skyrim with a butt-ton of mods? Open world games, tons of things to load on the fly.
It could still be CPU bottlenecked though. Tom’s Hardware did an article a long time ago about SSD load in gaming. The guy used some sort of trace-based analysis tool from Intel to check if the reads from the SSD during game startup, level loading, and playtime are sequential or random, what size, and what queue depth. It’s very interesting and I think many gamers would like to see such an article.
I’m looking at all the graphs and frankly it doesn’t mean much to me. I don’t run file servers, I load a ton of maps.
Thanks
Great review. I was hoping
Great review. I was hoping you could help out by comparing my workflow to which above benchmark best applies to me.
My apps use up to 29GBs of RAM where 1000s of 64k buffers are used as targets for various streams of audio stored on SSDs.
When I press a key on an 88 note keyboard/synth it goes 1st to the 64k buffer in RAM then a stream of audio follows.
Obviuosly random applies to the 64k RAM buffers and read to the streaming audio files.
Maybe the Workstation benchmark….?
Thanks again for a great source of comparisons on SSDs.
The X99 Sabertooth allow one
The X99 Sabertooth allow one to conceal their M.2 SSD completely under the Thermal Armor. Is that recommended given the heat output for SM951 NVMe?
HAPPY HAPPY JOY JOY!!!
HAPPY HAPPY JOY JOY!!!
Have you heard about a 1TB
Have you heard about a 1TB version of the SM951 being release soon?
I’m using the SM951 ACHI in a
I’m using the SM951 ACHI in a m.2 to PCI x4 card that has a heatsink on it and is plugged into a x4 PCI-E slot on my x99 motherboard. I love it but I’m wondering if I managed to get my hands on one of the new NVME, would it fit into the same heatsink slot (the pins looks the same) or would I have to use the M.2 slot on the motherboard? I’m assuming either would work and just change to NVME in the BIOS.
Second, I have two Samsung 850 pros running in RAID 0 as my applications drive. Would I still be able to keep this in RAID while using NVME on the Asus x99 motherboard?
Hello, I’ve just been
Hello, I’ve just been comparing a 512GB 951 NVMe variant that I purchased yesterday with an existing 512GB 951 AHCI. Apparently it’s a sample rather than a production unit but I’m seeing fantastic read speeds but horrific write speeds. In my case I’m using with an Asus Z97i-plus with the latest BIOS. The board identifies the 951 and allows me to install windows (8.1 all latest updates)… so far so good. Unfortunately when I run speed tests against the NVMe variant I get 10 times slower write speeds compared to the AHCI 951.
CrystalDiskMark: AHCI variant (connected to PCIe 3.0 bus)
Seq Q32T1 – 1172MB/s read | 1043MB/s write
4k Q32T1 – 398MB/s read | 289MB/s write
Seq – 1052MB/s read | 900MB/s write
4k – 35MB/s read | 128MB/s write
CrystalDiskMark: NVMe variant (connected to PCIe 3.0 bus)
Seq Q32T1 – 2264MB/s read | 501MB/s write
4k Q32T1 – 563 MB/s read | 21 MB/s write
Seq – 1299 MB/s read | 170 MB/s write
4k – 54 MB/s read | 0.98 MB/s write
Blindingly fast read but horrifically slow write speeds.
I’ve also tested using the Z97i-plus’s M.2 slot. I see reduced read speeds due to the limited, 10Gbps, speed of the M.2 on this board but the same horrific write speeds.
Is there something that I might be doing wrong? Could this be a BIOS problem? A Windows NVMe driver problem?
That’s odd, but I believe
That's odd, but I believe Kristian from Anandtech had a similar issue with one of his samples. It was an actual defect I believe and they had to swap out his sample, IIRC.