Samsung SM951 Write Speeds Low

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ihameed46

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Hi Forum,

I am running Windows 10 Pro on a Samsung SM951 NVME SSD (120GB) on a host adapter board (Lycom DT 120 M.2 pcie SSD to pcie adapter) in order to take full advantage of the NVME specification as my motherboard, an Asus Z-97 A/USB3.1, does not allow full pcie 3.0x4 speeds on the M.2 connector. On the native M.2 connector I was getting speeds of 714.5MB/s for Reads and 680.9 MB/s for writes, using Crystal DiskMark 5.1.0x64, as it is locked to a pcie2.0x4 speed.. So I bought the Lycom DT-120 board in order to access the pcie3.0 lanes on my mobo. So far so good. I needed no drivers and the drive was recognised in Windows10 Pro. Then I tried the speed check hoping to get the Read and Write speeds up above 1,000 MB/s but NO. Using the Seq option with 5 runs and 1GB file size I got 1573 MB/s for Read but very poor 674.1 MB/s for Write. I also tried the ATTO Disk Benchmark test and got similar readings for Write (but higher 2,000 MB/s for reads.

What could be hampering my results? Is it a faulty SSD? Have any forummembers noticed similar anomolies?

My system consists of an Intel I5-4690K, Asus z-97 A/USB3.1 mobo and 8GB of Corsair DDR3 RAM. Although the slower writes are not as intrusive as lower read speeds I am still annoyed that my painstaking upgrade has not totally delivered!! Any suggestions would be greatly appreciated.
 
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Leaps-from-Shadows

Leaps-from-Shadows

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Yes, like all SSDs, the 500/512GB version outperforms the 250/256GB version, which outperforms the 120/128GB version, and so on.

The sequential tests aren't as important for regular PC usage. The 4K random reads (bottom test in CrystalDiskMark) are more important as a general performance indicator. What are you getting for those, both with and without the adapter card?
 
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ihameed46

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Hi Leaps-from-Shadows, the 4K Random is even poorer at 52.19 MB/s for Read and 187.0 MB/s for Writes.The 4K (queue depth 32) gave readings of 743 and 266 MB/s. That is in the region of an SSD with AHCI interface on a Sata 3 connection. I didn't have time to take with out the card as that means opening up and switching back to M.2 connector.
 
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Leaps-from-Shadows

Leaps-from-Shadows

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Those are actually fairly normal scores. The 4K random reads and writes are lower for every single drive out there -- even regular hard drives. But the 950 Pro is nearly double the performance of SATA SSDs in the 4K random read, which is very good. And the 4K random write is usually 50% higher, which is also good.

My 512GB 950 Pro gets about 53Mbps for 4K random reads and about 190Mbps for 4K random writes in AS SSD. It gets about 60Mbps and 250Mbps for those tests in CrystalDiskMark. And that's from the M.2 port on my Z170 mainboard.
 
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ihameed46

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Hi Mcnumpty23, Thanks for your many responses. I found them very useful, especially the last one. I also get very low numbers for the last one(I believe 4K reading). Why is that? For my 128GB drive i am getting 52.19 for Reads and 187.0 for Writes (4K) and 743 for Reads and 266 for Writes on the 4K with queue depth of 32. Is this normal?
 
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mcnumpty23

mcnumpty23

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seems to be as expected

and at the end of the day benchmarks are one thing and real world use another

yes my 512gb benchmarks higher than your 128gb but these m2 drives are so fast any way i am not sure i would notice the difference in real life use between mine and yours

unless i had 2 of each and was copying files from one m2 drive to another

thats where i see these being great once prices fall more--lucky i got a board with 3 m2 slots in anticipation of these eventually taking over from regular ssds and prices getting much lower
 
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ihameed46

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Hi, where did you get your Samsung NVME drivers from. I have been looking too but Device Manager does not pick it up and nothing on Samsung's site either. It seems to be like gold dust!
 
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ihameed46

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Thanks. Much appreciated. I shall give it a try and let you know how I get on.
 
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mcnumpty23

mcnumpty23

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no problem not sure how much difference it makes over the microsoft nvme driver but its certainly newer

i never thought to test speed with the microsoft driver first before installing the samsung driver

and its still a bit peculiar in device manager/disks it still shows as the old microsoft driver

but once installed the samsung further down i got a new storage controller--samsung nvme controller
 
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ihameed46

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What is a storage controller? I thought all controllers were hardware components on the motherboard?
 
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mcnumpty23

mcnumpty23

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usually storage controllers are on the motherboard but pretty certain samsung nvme controller wasnt there till i installed the samsung driver

i mean everything works fine just peculiar to see that samsung nvme controller there--but never used a m2 drive before now so maybe thats normal and just needed the samsung driver to make it show up
 
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ihameed46

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Ok. Thanks. Much appreciate your promptness. I am also new to M.2 and NVME. There are a lot of people on Tomshardware that are having massive issues with M.2, SM 951, boot issues etc and I am trying to help them out. Every little helps to borrow from Tesco.
 
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