Samsung SM951 Clarification Questions

Timber · 23 Oct 2018 at 11:39

I have a couple of questions with regards to my old Samsung SM951 PCIE M.2 drive. I purchased it from here in July 2015 where it is listed as a 'Samsung SM951 512GB M.2 PCI-e Gen3 8Gbps x 4 Solid State Drive (MZHPV512HDGL-00000)' in my orders pages. I remember at the time there being two versions; a SATA and PCI-E NVMe version. And I'm reasonably certain I ordered the NVMe version.

Now I've listed it twice on a certain selling site and both times have had issues, I suspect because I haven't been 100% clear in the description (first time returned as not working, and 2nd time straight refund as I someone asked me whether it was a AHCI version). It also doesn't help that the part number seems to cover all different versions or the SM951 (i.e. MZHPV512HDGL). I assume there may be a way of identifying the part in Windows but was trying to avoid this as this means having to install in my laptop again and I suspect running some software.

If I google what's in my OCUK My Orders page then this page is returned:
SM951 512GB M.2 PCI-E GEN3 8GBPS X 4 AHCI SOLID STATE DRIVE (MZHPV512HDGL-00000)

I used this in my MSI X99A Gaming 7 motherboard and have since tested it in my ASUS Strix GL703GS and it allows me to install Windows 10 fine (and I was using fine on my MSI Motherboard). Given the ASUS Strix GL703GS includes a PCI-E M.2 SSD (option noted as NVMe on the specifications pages, and for me is a Samsung SM961) this makes me think the drive is an NVMe drive although both setups seem to support both AHCI and NVMe drives.

However I'm pretty certain I have a NVMe version of this drive. At the time of the order I remember there being a SATA and PCI-E version of the M.2 drive and I specifically ordered the latter. And if I look at this PC site picture my drive appears to look closer to being the NVMe version, rather than the AHCI version: https://www.pcper.com/image/view/55305?return=node/62777. However my SM951 doesn't say AHCI on it, although it has the second barcode in the center to confuse things.

My SM951 drive:

So because I'm not an expert on storage and my memory may be playing tricks:

1. Is the AHCI version the SATA version, and the NVMe the PCI-E version?
2. If so and if I adjust the name of the part to the 'Samsung SM951 512GB NVMe M.2 PCI-e Gen3 8Gbps x 4 Solid State Drive (MZHPV512HDGL-00000)' this should clear up any confusion?
3. Are there only 2 variants of the SM951?

Sorry for the long winded post, but I'm sick of this part causing me problems in trying to find it a new home and wanted to clarify.

Thank you in advance.

EDIT: - just to add my drive looks close to the top drive in the first picture of the Anandtech review of the SM951 256GB NVMe drive in July 2015: https://www.anandtech.com/show/9396/samsung-sm951-nvme-256gb-pcie-ssd-review

Journey · 24 Oct 2018 at 08:00

There is only one type of SM951 drive, which PCI-e NVMe 4x, and fits the compatible M.2 NVMe slots on motherboards and in certain laptops. Other M.2 drives can be SATA based (or AHCI as you call it) but the gold finger connector has a different layout so it is easy to tell them apart, it has two notches, not just one like yours.

I think the problem you have been having is most people don't have a clue, and do no research before buying these things and just think "Oh I have an M.2 slot that will work just fine and the read/write speed look pretty fast" If some one buys it from you ask what they are installing it in before you post it, make model etc. I've sold quite a few of these drives and like you had people saying they cannot get them working, so now I vet them before I trust them not to return it.

Timber · 24 Oct 2018 at 09:38

@Journey - Ty for the reply. I think you are definitely right that some vetting is required on these parts, although in both case the two successful bidders weren't exactly open as to what they were installing this in, the first adding they have a 'gaming PC' if they can't get it to work in a Macbook.

With regards to the SATA version I think this must have been the Samsung SM871, which as you say has a different type of connector.

However there does appear to be 2 variants of the SM951 though, with a revision being based on an AHCI firmware and another with a NVMe firmware. The official Samsung Product Overview is of zero use as it only lists one NVMe version. A few places (ironically) including that Anandtech SM951 256GB review above list this point:

Distinguishing the AHCI and NVMe version from each other isn't very simple as the difference lies in a single character in the model number. The AHCI version carries the code MZ-HPVxxx0 (where xxx is the capacity in gigabytes), whereas the NVMe version is called MZ-VPVxxx0.

A user (possible Australia etailer) on the Tom's Hardware pages states the same, and the same site ran a comparison of the AHCI vs. NVMe here.

In the shot above, the NVMe model is on the top; you can identify it by the third letter in the part number. The NVMe model is designated by a V, while the AHCI model has an H.

Although Tom's didn't pick up on the firmware difference in their earlier May 2015 review.

My drive has the 'H' model number and also appears to have the earlier Firmware (BXW2500Q) which the AHCI version had even if the drive didn't state ACHI version on it (at a guess this happened on later models). The numbers after the P/N appear to relate to the OEM being supplied, i.e. 00001 = Lenovo etc. Based on the sources it appears Samsung used AHCI firmware in their earlier SM951's although the definitely kept selling these as you can see from product pages on most etailers sites.

As you can see I spent far too much time reading up about this part!

I think the solution is to avoid selling to Apple owners (or resellers) where the AHCI version is more sought after than the NVMe version because there are difficulties getting this to work with OSX. And given I've had one Apple Macbook owner unable to get it to work, I don't really want to sell it on to an Apple person again for fear of another return. I know the drive works well in a Windows PC and need to try and fine someone that wants to use it in a Windows PC, which will work with either the AHCI or NVMe version of the drive.

Journey · 24 Oct 2018 at 09:48

My apologies, you are indeed correct the firmware on this drive can be a specific AHCI variant, which does seem to be prevalent from large OEM's like HP/Lenovo etc. Either way both are PCI-e only, and as such should work in any PC motherboard that supports M.2 NVMe, so good luck with your sale.

Timber · 24 Oct 2018 at 11:08

Indeed, and thank you. Yep having never owned a SATA version I initially and incorrectly thought that might be my issue. I suspect it's just those pesky Apple owners causing me probs.