SM951 - Slow speeds

[bocajls]

Hello everyone!

I recently bought myself a 256GB SM951.
After testing it, i felt quite disappointed by the CrystalDiskMark4 results.


Samsung SM951 M.2 SSD:

4 times with 2GiB run

Seq Q32T1:
Read: 716.4 Megabytes / second
Write: 810.1 Megabytes / second

4K Q32T1:
Read: 170.4 Megabytes / second
Write: 179.6 Megabytes / second

Seq:
Read: 723.5 Megabytes / second
Write: 764.5 Megabytes / second

4K
Read: 40.59 Megabytes / second
Write: 95.23 Megabytes / second

For comparison, i tested my sata 3.0 ssd.

Samsung 850 250GB EVO

4 times with 2GiB run

Seq Q32T1:
Read: 549.7 Megabytes / second
Write: 506.4 Megabytes / second

4K Q32T1:
Read: 300.1 Megabytes / second
Write: 271.7 Megabytes / second

Seq:
Read: 531.2 Megabytes / second
Write: 502.3 Megabytes / second

4K
Read: 44.06 Megabytes / second
Write: 126.2 Megabytes / second


The 256GB SM951 specs says:
Read: 2150 Megabytes / second
Write: 1200 Megabytes / second

I thought it might have been because of the fact that the m.2 on my motherboard only goes to 10Gbps, but even that should result in readings near the 1,25 Gigabytes / second.

Clearly something isn't fully compatible or configured incorrectly.
I appreciate all the help I can get, thanks in advance!

 

[JohnnyLucky]

1. What is the brand and model of your motherboard?

2. Run ATTO benchmark and post results.

 

[bocajls]

1. What is the brand and model of your motherboard?

2. Run ATTO benchmark and post results.

MSI Z97 Gaming 7 motherboard.
http://www.msi.com/product/mb/Z97-GAMING-7.html#hero-overview

ATTO benchmark:

Transfer size: 0.5 to 8192.0 KB
Total Length: 256MB
Overlapped I/O
Queue Depth: 4

0.5 = 14009 Write, 20811 Read.
1.0 = 28784 Write, 41728 Read.
2.0 = 62308 Write, 81444 Read.
4.0 = 131620 Write, 146795 Read.
8.0 = 276627 Write, 246382 Read.
16.0 = 294895 Write, 360120 Read.
32.0 = 714879 Write, 478961 Read.
64.0 = 720240 Write, 612704 Read.
128.0 = 720415 Write, 416570 Read.
256.0 = 720415 Write, 725738 Read.
512.0 = 720192 Write, 738813 Read.
1024.0 = 720192 Write, 734524 Read.
2048.0 = 721953 Write, 742217 Read.
4096.0 = 721953 Write, 743931 Read.
8192.0 = 720192 Write, 738813 Read.

 

[Dereck47]

Your benchmark results are normal.

The M.2 slot on your motherboard is PCIe 2.0 x2 with a bandwidth up to 10Gb/s.
http://us.msi.com/product/mb/Z97-GAMING-7.html#hero-overview

In order to get advertised Read/Write speeds from your SM951 you need an x4 slot with a bandwidth up to 32Gb/s.

 

[JohnnyLucky]

There is good news and bad news. There is nothing wrong with the Samsung SM951 M.2 3.0 x 4 solid state drive. There is nothing wrong with the M.2 2.0 x 2 port on your MSI Gaming 7 motherboard. The real problem is that your motherboard and ssd are mismatched. The Samsung SM951 requires 4 PCIe 3.0 channels for proper operation. The M.2 slot on the motherboard only uses 2 PCIe 2.0 channels. There is a very big difference between using 4 PCIe 3.0 channels and using just 2 PCIe 2.0 channels.

The M.2 2.0 x 2 rating of 10Gb/s is theoretically the upper limit. However, for technical reasons the maximum read speed is limited to about 740MB/s and write speeds are even lower. Your ATTO benchmarks look good for an M.2 2.0 x 2 ssd. The benchmark pretty much matches results in technical reviews. The results are also similar to the Plextor M6E which is a 2.0 x 2 ssd.

 

[bocajls]

There is good news and bad news. There is nothing wrong with the Samsung SM951 M.2 3.0 x 4 solid state drive. There is nothing wrong with the M.2 2.0 x 2 port on your MSI Gaming 7 motherboard. The real problem is that your motherboard and ssd are mismatched. The Samsung SM951 requires 4 PCIe 3.0 channels for proper operation. The M.2 slot on the motherboard only uses 2 PCIe 2.0 channels. There is a very big difference between using 4 PCIe 3.0 channels and using just 2 PCIe 2.0 channels.

The M.2 2.0 x 2 rating of 10Gb/s is theoretically the upper limit. However, for technical reasons the maximum read speed is limited to about 740MB/s and write speeds are even lower.

I see, thanks a bunch !

 

[bocajls]

Your benchmark results are normal.

The M.2 slot on your motherboard is PCIe 2.0 x2 with a bandwidth up to 10Gb/s.
http://us.msi.com/product/mb/Z97-GAMING-7.html#hero-overview

In order to get advertised Read/Write speeds from your SM951 you need an x4 slot with a bandwidth up to 32Gb/s.

Thanks a lot, I guess I'll just have to buy a new motherboard if I want to utilise its full potential

 

[Crooksed]

Hello bocajls,
I had the same problem then I bought a pcie adaptator (you fix the ssd on the card then plug into a pcie x4 minimum port). And that works good, the read/write was 700-740 and went to 1600-1650.

Now I speaking to every readers of this post :
That's awesome but now my problem is, why my performances are stucked at 1600mo/s ? this ssd have to read at 2150mo/s. Maybe it's my adaptator ? But I'm sure that I pluged it on a x4 pcie 3.0 port. Is my ssd was built on a bad run ?

Thanks for your answers.

(Sorry for the bad english, I am french)

Crooks

 

[JohnnyLucky]

Crooksed - What is the brand and model number of your motherboard? What is the brand and model number of the PCIe adapter card?

 

[Crooksed]

So, my motherboard is an Asus Ranger VII, and the adapter is this one : http://www.amazon.fr/gp/product/B00MYCQP38?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

I don't have a lot of details on it, I just know that it's for M.2 M type (or H I often counfound), it is made for 3.0 pcie, accept the 2.0, and this is a x4.

As I said I pluged the adapter into a 3.0 pcie port, this port is the second x16 for a second graphic card, I looked on a lot of forums and it looks ok, and it is my only way to get a x4 + 3.0 pcie.

 

[The Original Ralph]

here's the one i'm using ($19 + shipping) http://www.addonics.com/products/adm2px4.php

and it appears to be the identical twin to the Lycom, so one of them is manufacturing the unit and private labeling it for the other to sell as their own

I had the same issue - in my M.2 slot on a Z97 mobo, i was seeing 770 - 810 MB/s read, 510 - 540 MB/s write with my xp941 (my M.2 slot was "x2"). When i moved the xp941 to the addonics PCIe > M.2 adaptor expansion card, speeds jumped to 1180 MB/s read, 870 MB/s write which is just shy of the 1200/900 samsung quotes in it's specs

the PCIe slot i installed it in is PCI 2.0 x4

fwiw

 

[Crooksed]

I'm not an expert but I think your perf are good, you have 97% of the maximum mentioned for a xp941, so it's very good, compared to me, I have 74% of maximum...

So, does anyone knows ?