Talk:M.2/Archive 1

This is an archive of past discussions about M.2. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page.

Archive 1

Requested move 29 October 2013

The following discussion is an archived discussion of the proposal. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section.

The result of the proposal was

Next Generation Form Factor → M.2 – "Next Generation Form Factor" is the name which has been initially used for this standard / SATA form factor, and it's been replaced with "M.2" name all around the references etc. Though, "M.2" article already exists as a redirect page, so this move needs to be performed by an admin. Thank you. Dsimic (talk) 19:46, 29 October 2013 (UTC)

Survey

Feel free to state your position on the renaming proposal by beginning a new line in this section with *'''Support''' or *'''Oppose''', then sign your comment with ~~~~. Since polling is not a substitute for discussion, please explain your reasons, taking into account Wikipedia's policy on article titles.

Discussion

Any additional comments:

The above discussion is preserved as an archive of the proposal. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

M.2 is a connector and not an interface

Tyco Electronics describes the M.2 (NGFF) connector as being able to support PCI Express 3.0, USB 3.0, and SATA 3.0. The connector can be specified with different keys for different uses [1].

specifically, M.2 is a connector and not an interface. multiple interfaces are supported by keying on the connector.

This will be much clearer when a standard is agreed. Blouis79 (talk) 02:16, 12 January 2014 (UTC)

Hello there! You're right, and the article already states that clearly, stating that M.2 "is a specification for computer expansion cards and associated connectors". — Dsimic (talk) 02:21, 12 January 2014 (UTC)

Lengths and compatibility

I notice there are multiple lengths of card, can each socket only take one length of card or are there provisions to allow installation of shorter cards in longer sockets? — Preceding unsigned comment added by 151.229.191.223 (talk) 00:00, 22 June 2014 (UTC)

That doesn't seem to be specifically covered by the M.2 specification as a design requirement. However, from what I've seen (and what seems to be logical, of course) M.2 sockets support multiple lengths of M.2 modules, meaning that the sockets capable of accepting longer M.2 modules also accept shorter ones. As an example, please have a look at this M.2-to-PCIe adapter where different positions for the mounting screw are clearly visible.

At the same time, I'll see to integrate this information into the article as well. — Dsimic (talk | contribs) 03:46, 22 June 2014 (UTC)

Done, expanded the article a bit. — Dsimic (talk | contribs) 05:58, 22 June 2014 (UTC)

Keying diagram is incorrect (reversed)

Does anyone else agree that the keying diagram is reversed? For example, it shows a B-key with male connector (not the socket) with the connector pointing toward the top of the image and the body of the M.2 device implied to fall off the bottom of the image. I also assume that this theoretical M.2 device is facing "top side visible" to the viewer, meaning that the viewer is looking at the same side of it that they would see if they were looking at a real device (about to be) inserted into a socket from above the circuit board.

In such a case, the B-key hole would be on the LEFT of the male M.2 device, but this image depicts the key hole on the RIGHT of the male M.2 device, which seems wrong given the presumed orientation of the device in the picture.

Obviously, the M-key device and socket is also backwards. Before I fix it, I hope someone else can just make sure I am not insane. This is hard to describe in words. If you need a citation to prove what I mean and don't want to look for one on your own, let me know.

Surlyhacker (talk) 22:39, 3 September 2014 (UTC)

To be clear, there is a perspective from which this diagram makes sense, but it is not the most intuitive real-world perspective, and perhaps it could be fixed by some additional labeling, using a real photograph, and/or a 3D view.

Surlyhacker (talk) 23:26, 3 September 2014 (UTC)

Hello there! You're totally right, depicted sockets and edge connectors are all turned upside-down. In other words, the drawing is technically correct but it isn't naturally oriented; there isn't much need for some complex references, having a look at a few images is enough (image #1, image #2, image #3 or image #4). Great catch, thumbs up! How have I managed to miss all that? :)

I'll add a request to the Wikipedia:Graphics Lab/Illustration workshop so SVG drawing is edited for the natural orientation – that should be much better than introducing various additional labeling, which could be confusing. Hope you agree. — Dsimic (talk | contribs) 23:43, 3 September 2014 (UTC)

Done, please check it out. — Dsimic (talk | contribs) 22:39, 4 September 2014 (UTC)

Dsimic The bottom row of the diagram is still incorrect. The 5 and 6 wide sections in the B & M diagrams are correctly labelled but on the wrong sides. Most people will not notice or care. My SVG editor is on anther computer so will not be editing this myself. Idyllic press (talk) 18:56, 6 April 2015 (UTC)

Hello, Idyllic press! Could you, please, elaborate a bit on why is the drawing incorrect? Please also have a look at the above linked pictures of real M.2 modules, which confirm that the currently depicted orientation is correct (or more natural, depending in how do you look at it): image #1, image #2, image #3 and image #4. — Dsimic (talk | contribs) 22:24, 6 April 2015 (UTC)

Ah, now I see. Great catch, thank you very much for pointing it out, will get the "B & M key" example corrected. — Dsimic (talk | contribs) 22:27, 6 April 2015 (UTC)

Done, please check it out. — Dsimic (talk | contribs) 23:20, 6 April 2015 (UTC)

M.2 is not SATA Express

M.2 is a connector and form factor completely different than SATA Express. The SATA Express specification came from SATA-IO, whereas the M.2 specification is from PCI-SIG. PCI-SIG does not use the term SATA Express to describe M.2. — Preceding unsigned comment added by 192.55.55.39 (talk) 17:32, 14 July 2015 (UTC)

That's a very good point, will make the required changes to the article later today. Thank you for pointing it out! — Dsimic (talk | contribs) 20:54, 14 July 2015 (UTC)

It's a bit more complicated as the M.2 is covered by both PCI-SIG (the M.2's PCI Express part) and SATA-IO (SATA revision 3.2 describes the M.2's SATA part), see this paper for further information. Will get that incorporated into the article as well. — Dsimic (talk | contribs) 00:32, 15 July 2015 (UTC)

Done, IMHO it's much better now. — Dsimic (talk | contribs) 03:21, 15 July 2015 (UTC)

Split personality

This article has a split personality:

In the first few paragraphs of the Features section it is explained that M.2 is in interface that replaces Mini PCI Express, while also giving access to various other buses (USB, DisplayPort, SATA, ...)
The rest of the article is written as if M.2 is "just" a storage interface replacing mSATA.

AFAIK the first personality is the right one. —Ruud 21:48, 22 October 2015 (UTC)

Hello! As we know, M.2 is pretty much primarily used in storage applications, which is also the main reason why it has been invented. Sure, there are M.2 Wi-Fi cards, for example, but there isn't much to write home about them, so to speak, :) which is the reason why the M.2 § Features section focuses on storage applications. The rest of the article is IMHO rather application-neutral, describing that M.2 replaces the mSATA standard, which uses the existing PCI Express Mini Card form factor and connector. Hope you agree. — Dsimic (talk | contribs) 05:09, 23 October 2015 (UTC)

Just to add, it is according to various sources that M.2 hasn't been invented to replace the PCI Express Mini Card form factor; it has actually been invented to replace the mSATA standard. The article simply follows the sources in that regard. — Dsimic (talk | contribs) 05:14, 23 October 2015 (UTC)

But only B and M-keyed slots are intended for SSDs. A and E-keyed slots really are mostly/only for non-storage (Wifi/Bluetooth/etc.). I think it wouldn't be a problem for the majority of the article to describe the storage-related aspects, but it needs to be separated more clearly from the more general aspects of the bus as is currently done. (E.g., move the table about keying up and put the stuff about SATA/AHCI/NVMe etc. in a separate subsection.) —Ruud 14:26, 23 October 2015 (UTC)

That's a good suggestion, later today I'll refactor the article a bit. — Dsimic (talk | contribs) 14:25, 25 October 2015 (UTC)

What does the second photo show?

I am looking at the second photo and can't see where the M.2 connector is shown? I can see the USB connectors, the chassis fan connector and the two switches for on / off and reset as well as the panel connectors but it is not obvious, to me at least, where the M.2 connector is in the photo. Yes it says M.2 x4 on the board itself but any connector seems to be missing to me. Regards, Paul Heywood — Preceding unsigned comment added by 194.74.194.224 (talk) 15:13, 9 March 2016 (UTC)

I believe the slot to the left of the "TPU" chip is the M.2 slot and the two screw holes to the right of it are for securing the 2260 and 2280 form factors respectively. But I agree it's not a very good photo and it would be better if the relevant components were highlighted. -- intgr [talk] 09:28, 10 March 2016 (UTC)

Hello! You're right, those are the exact locations of the M.2 socket and mounting posts, and I agree that it wasn't that obvious from the picture. I've improved the image caption to provide a better description, and improved the picture (File:M.2 connector on a computer motherboard.jpg) itself by labeling the M.2 socket and two mounting posts. It should be all clear now. — Dsimic (talk | contribs) 12:32, 4 April 2016 (UTC)

PCI-Express 3.0 x4 speed fallback?

Will the faster M.2 PCI Express cards work in older computers with a slower / older PCI Express bus? Does the M.2 bus gracefully fall back for slower bus speeds?

The particular scenario where this arises, is using an PCI-Express 3.0 M.2 M-keyed x4 SSD in a riser card, to plug it into the x16 video card slot of a older desktop computer with PCI Express 1.0, 1.1, or 2.0.

-- DMahalko (talk) 03:36, 5 May 2016 (UTC)

Hello! Please note that Wikipedia is not a forum, so the talk pages should be used only for discussing possible article improvements. However, as described in the article, M.2 exposes native PCI Express bus, which ensures backward and forward compatibility. — Dsimic (talk | contribs) 22:27, 7 May 2016 (UTC)

"as of April 2014, host-side connectors are available with only one mating key position populated (either B or M)"

I couldn't find this stated in any of the three references given. Either way, it's simply not true. M.2 slots intended for WLAN cards are commonly A or E keyed. From my own experience, I can say that the ThinkPad T450s and Latitude E5470 both have A-keyed M.2 slots populated with WLAN cards, and these were released in 2015 and 2016. Perhaps what was meant is that SATA-supporting M.2 slots are now keyed with either B or M and not both. --Juventas (talk) 00:08, 15 May 2017 (UTC)

M.2 replacement mounting screw?

Is the screw size and type standardized? We bought a laptop recently with an empty 80mm M.2 slot, and they didn't include the mounting screw.

I don't see any info about the screw size/type this in the article. -- DMahalko (talk) 03:47, 5 May 2016 (UTC)

Hello! That's a very good question, but unfortunately I haven't seen that kind of information in any of the available references. I'll have a look again, though. — Dsimic (talk | contribs) 22:29, 7 May 2016 (UTC)

In fact I have seen M2 and M2.5 screws to mount M.2 modules. I have also heard that even M3 screws are used in some cases. The size of the notch in the M.2 module would technically allow that. But, the most common screw size for standard situations like mounting an M.2 module on a circuit board or M.2 to PCI-E adapter, is M2x3 with flat-head (Thread diameter 2.0mm, length 3.0mm, thread-pitch 0.4mm). I have added this information to the respective section. - Gurit (talk) 23:35, 13 September 2017 (UTC)

is Socket and Gen interchangeable

Are socket 2, socket 3 interchangeable with gen2 and gen3? I suspect they are but I can't find a good reference. Thomas d stewart (talk) 14:19, 23 January 2019 (UTC)

NO. The gen(eration) of what ? PCIe ? Sata ? anyway, no .. socket 2= B notched and socket 3 is M notched. that is all.

any card may have both notches if it felt like it. whether it runs.. well thats up to the design of the card :) The notch only exists to remind the human not to put a card requiring USB or other comms into a socket that doesn't provide them.

This is really a stupid thing ... wasting sata and USB interfaces if its a PCIe device plugged in... They should have just miniturised PCIe 4x slot, so that we could just put an adaptor on if we wanted to use it as regular PCIe 4x. Motherboard designers should avoid M.2 and used the direct to CPU PCIe lanes on PCIe slots... We might have been able to redirect the CPU PCIe lanes to the PCIe slot of our choosing already ? That way we would have PCIe slots with unshared PCIe lanes ready for RAID cards, and 10 socket USB3 cards and things like that.Currently we only get the GPU socket(s) with CPU lanes (16 lanes.. if 2 sockets then 8 each ? ), and then the rest share the chipset lanes. The alternative would be ,if the number of available lanes made it worth while, was that the chipset configurator would allow choice if where the CPU lanes are allocated, and even of how to share the bandwidth of the chipset lanes. eg , dedicate half to the extra full PCIe slot ? 3/4 ? or just let it share with motherboard SATA ? etc

Thats what the article is missing.. the discussion that the M.2 slot is stupid and may as well be a PCIe slot. If laptops wanted a slot that can be used for SATA drives or USB 3 expansion, they could have made a SPACE with PCIe 4 at one end, and an mSATA connector at the OTHER end.. so that the M.2 did not have to maintain mSATA / B notch/socket 2 etc compatibility... the laptop people wanted one SPACE for both uses.. well that really didnt need a mixedbred socket. Just put two sockets on one space !

27.96.199.11 (talk) 11:32, 2 September 2020 (UTC)

Confusing, if not plainly wrong, text

The article says "SATA M.2 cards [...] have three connector notches while PCIe M.2 cards have only two." Next to that text there is a photo showing a SATA MM.2 card, with two notches in the connector, and a PCIe M.2 card with one notch in the connector. Eiher the text is plainly wrong, or I'm not getting the intention behind the wording. I'm tempted to edit the ext, but I suspect that I'm misreading (since otherwise the error in the text would be so blatant).

IIs this about a misuse of the wwrd "notch"? A notch is an "angular cutout" and looking at the image there clearly is two and one cutout, respectively. Not three and two.

— Preceding unsigned comment added by 194.218.10.146 (talk) 11:59, 25 September 2019 (UTC)

Those words about 2 and 3 notches seem vandalism.. or someone with a poor understanding of english, and of M.2 The location of the one notch chooses between them, not the number. If there are 2 notches, then thats rather specific, its notched at both locations, its got the capabilities of both.

27.96.199.11 (talk) 12:10, 2 September 2020 (UTC)