7 ms·

However, of course, it can cause confusion of the “it fits, but doesn’t work” kind. For instance, a B+M key SATA SSD will not work in some NVMe-only M-key socke

However, of course, it can cause confusion of the “it fits, but doesn’t work” kind. For instance, a B+M key SATA SSD will not work in some NVMe-only M-key sockets, and some proprietary standards like CNVi throw a wrench into the “any M.2 WiFi card will work with your laptop” concept. This is what I hate about M.2. If I plug something into a SATA port or USB port I know it's going to work. Why the hell would you bother making a keyed standard where matched-key products don't have to be compatible with one another?

londons_explore 4y ago
I think the designers of M.2 weren't powerful enough to force use of a specific signalling standard. Some people wanted a connector for sata, others wanted PCIE, some wanted USB... Nobody wanted to design new protocols or have to use new chips. So we ended up with a standard where both sides can support one, two or three of those...
- Dylan16807 4y ago
  Sure, but that's what the keys are supposed to be for.
londons_explore 4y ago
Not only might it not work... Some combinations that physically fit actually blow up the host...
- NavinF 4y ago
  I call bullshit. What's your source?
  - dylan604 4y ago
    Blow up might not be exactly right, but I could imagine smoking a chip or some other method of frying some electronic component. If you send 12v by mistake down a line connected to a component only expecting 3.3v or 5v, then it could easily fry it. I'm guessing most components at this stage of the board have been assumed a good voltage and might not have anything inline between the M.2 connector and the component to spill any extra volts.
    - NavinF 4y ago
      If you google "m.2 pinout", you'll find that none of the variants use 12V and 5V on the same pins. It's almost like the people who design these things know what they're doing.
      - dylan604 4y ago
        Doesn't mean someone buying a connector like this to DIY their own thing know what they are doing
        NavinF 4y ago
        That's a truism. You could say that about any connector.
        dylan604 4y ago
        Right, but you called bullshit. I was just providing how/why it might not necessarily be bullshit. When it comes to DIY which this product is aiming, anything is possible.
      - londons_explore 4y ago
        But some use 3.3 volts or gnd on pins that others use as data output pins. That will blow up the output driver MOSFETs.
  - jasonjayr 4y ago
    I've personally toasted 2 x M.2 NVME Boards confusing them with M.2 SATA. The key was close enough that I didn't realize the expensive error.
    - wtallis 4y ago
      You mean you forced an M-key drive to go upside down into a B-key slot despite the misalignment of the key? I think I've only ever found B-key slots in adapter cards that have one M-key slot for an NVMe drive and one B-key slot for a SATA drive, but it would be hard to miss the distinction when they're right next to each other like that.
  - londons_explore 4y ago
    https://pcisig.com/sites/default/files/files/M.2%20Interoperability%20Warning_0.pdf https://pcisig.com/sites/default/files/files/M.2%20Interoper...
    - NavinF 4y ago
      Thanks, TIL!
progman32 4y ago
This is my issue with USB-C. Love the connector otherwise.
- lostlogin 4y ago
  You haven’t lived until you have bought a cable, had it work, then bought another with the same specs from the same vendor with the same packaging, and had it not work. IT support for a fleet of USB-C monitors is actually awful.
  - Teknoman117 4y ago
    The solution to this is to only buy thunderbolt+pd cables. If not everyone wants to deal with the chunkiness, also maybe deploy some "base" thunderbolt cables where power delivery beyond the base 20W spec isn't required. This is what I do. Thunderbolt can't and won't function unless the cable meets the specifications, and thunderbolt cables have every conductor populated. This means that USB, DisplayPort, and USB-C Alt modes work over them as well. Long version: On any given USB-C cable you have either zero or four high-speed lanes at 5, 10, or 20 Gbps max signalling. Zero pairs is USB 2.0 only and is typically bundled with smartphones (grumble) or USB-C chargers. No USB 2.0 pair probably also exists somewhere but I've not encountered one yet. The "PD" wattage of a cable is whatever the current rating of the VBUS wire is times 20. All power delivery is is running the VBUS wire at 20V instead of 5V and the sideband protocol to agree on boosting the voltage and finding out what the max voltage and current of the source is. Thunderbolt requires the fastest of the differential lane configurations and if you get thunderbolt + PD, you know the max VBUS current of the cable.
    - edude03 4y ago
      Yes, but for people thinking of going down this path, the cables are $120 and pretty thick so it’s not without trade offs
      - Teknoman117 4y ago
        Not really. $120 for the Apple branded two meter cable for sure, but the third party ones run about $30/meter. I bought a handful of the one meter "Cable Matters Thunderbolt 4 40 Gbps" cables off Amazon for $30 each. I run one from a Dell XPS 15 laptop pulling up to 100W to a dock. They are quite chunky though. Beware anything longer than 2 meters that isn't an active cable though. The differential lanes will probably drop to 10 Gbps. Fine for USB 3, 3.1, and 3.2x2 but you'll lose half the USB4 bandwidth. --- I'm not sure if Thunderbolt allows for lane speed degradation. You see some "thunderbolt 3 20gbps" cables but I don't know if that's two pairs at 10 Gbps or one pair at 20 Gbps. Now you've got this whole USB4 mess - USB 4 and Thunderbolt 4 are the exact same protocol and physical layer, same controllers and everything. The difference is whether the device or host adheres to the performance specification and paid for certification.
theodric 4y ago
Until some bright spark had the idea to make Thunderbolt 3 share a connector with USB-C. And then Apple (inter alia) released laptops that were either USB-C+Thunderbolt 3 -or- purely USB-C (12" MacBook), making life complicated for folks doing IT support in mixed environments. It Just Works, Unless It Doesn't™
- lostlogin 4y ago
  Ah, you too enjoy the dongle lifestyle. Apple seems to be moving things forward, where others still keep some seriously legacy options, but neither option is pain free.
- eigen 4y ago
  hasn't this always happened with internal connectors? SATA rev 1 (1.5Gbps, 2003) used the same connector as SATA rev2 (3Gbps, 2004) & SATA rev 3 (6Gbps, 2009) so drives and motherboards plugged together and operated but at the slowest common speed between them. is USB-C somehow different that people expect Thunderbolt 3 (Dec 2015) using a connector introduced in Aug 2014 on a 12" Macbook announced in March 2015?
  - izacus 4y ago
    No, this was always an issue, even in times when you enjoyed yourself with incompatibilities between different RS-232 implementation, VGA cables, DVI digital/analogue mess, FireWire burning out ports and more. The world where a plug was enough to identify underlying protocol in 100% of never fail cases never existed. However, nostalgia deletes enough memory for us to whine about times that never existed ;)
oakwhiz 4y ago
I've been having mechanical problems with M.2. Not only does it specify very thin PCBs for no good reason, but variable length, width, and different fasteners make M.2 a rather annoying form factor for me personally. In addition to problems caused by thermal characteristics or vertical depth used up by heatsinks. It's not always possible to locate a fastener that will work in a given board, or even remove it from the top side without completely disassembling a machine. Not all boards are x86 PCs or servers either, M.2 is now used in embedded devices and some assumptions can't be taken for granted there. If you look at PCI or PCI Express there is a mechanical component to the case and socket which holds on to the card so that it's not just floating there. However M.2 capable boards seem to have a wide variety of fasteners, and that's the only thing holding it in. There is no standard part for this, and good luck if you need a replacement or it wasn't included in the stock machine. I've also watched an employee of a computer store install an M.2 card in a bent position because the included fasteners were not even capable of correctly holding the card. Why is it so easy to mis-install in the first place?
wumpus 4y ago
I'm a guilty party for reusing a connector because it already existed -- we wanted to make a HyperTransport slot standard (HTX), so we used 2 PCIe standard connectors. We placed them at an unusual depth from the edge so it was unlikely that anyone would accidentally plug an actual PCIe card into them. But I'm sure someone was confused by it at some point.
nsxwolf 4y ago
I got this NVMe wifi card that uses some key that basically only exists for motherboards and laptops with special NVMe wifi card slots. I couldn’t use it or find an adapter.

londons_explore 4y ago

I think the designers of M.2 weren't powerful enough to force use of a specific signalling standard. Some people wanted a connector for sata, others wanted PCIE, some wanted USB... Nobody wanted to design new protocols or have to use new chips. So we ended up with a standard where both sides can support one, two or three of those...

Dylan16807 4y ago
Sure, but that's what the keys are supposed to be for.

londons_explore 4y ago

Not only might it not work... Some combinations that physically fit actually blow up the host...

NavinF 4y ago
I call bullshit. What's your source?
- dylan604 4y ago
  Blow up might not be exactly right, but I could imagine smoking a chip or some other method of frying some electronic component. If you send 12v by mistake down a line connected to a component only expecting 3.3v or 5v, then it could easily fry it. I'm guessing most components at this stage of the board have been assumed a good voltage and might not have anything inline between the M.2 connector and the component to spill any extra volts.
  - NavinF 4y ago
    If you google "m.2 pinout", you'll find that none of the variants use 12V and 5V on the same pins. It's almost like the people who design these things know what they're doing.
    - dylan604 4y ago
      Doesn't mean someone buying a connector like this to DIY their own thing know what they are doing
      - NavinF 4y ago
        That's a truism. You could say that about any connector.
        dylan604 4y ago
        Right, but you called bullshit. I was just providing how/why it might not necessarily be bullshit. When it comes to DIY which this product is aiming, anything is possible.
    - londons_explore 4y ago
      But some use 3.3 volts or gnd on pins that others use as data output pins. That will blow up the output driver MOSFETs.
- jasonjayr 4y ago
  I've personally toasted 2 x M.2 NVME Boards confusing them with M.2 SATA. The key was close enough that I didn't realize the expensive error.
  - wtallis 4y ago
    You mean you forced an M-key drive to go upside down into a B-key slot despite the misalignment of the key? I think I've only ever found B-key slots in adapter cards that have one M-key slot for an NVMe drive and one B-key slot for a SATA drive, but it would be hard to miss the distinction when they're right next to each other like that.
- londons_explore 4y ago
  https://pcisig.com/sites/default/files/files/M.2%20Interoperability%20Warning_0.pdf https://pcisig.com/sites/default/files/files/M.2%20Interoper...
  - NavinF 4y ago
    Thanks, TIL!

progman32 4y ago

This is my issue with USB-C. Love the connector otherwise.

lostlogin 4y ago
You haven’t lived until you have bought a cable, had it work, then bought another with the same specs from the same vendor with the same packaging, and had it not work. IT support for a fleet of USB-C monitors is actually awful.
- Teknoman117 4y ago
  The solution to this is to only buy thunderbolt+pd cables. If not everyone wants to deal with the chunkiness, also maybe deploy some "base" thunderbolt cables where power delivery beyond the base 20W spec isn't required. This is what I do. Thunderbolt can't and won't function unless the cable meets the specifications, and thunderbolt cables have every conductor populated. This means that USB, DisplayPort, and USB-C Alt modes work over them as well. Long version: On any given USB-C cable you have either zero or four high-speed lanes at 5, 10, or 20 Gbps max signalling. Zero pairs is USB 2.0 only and is typically bundled with smartphones (grumble) or USB-C chargers. No USB 2.0 pair probably also exists somewhere but I've not encountered one yet. The "PD" wattage of a cable is whatever the current rating of the VBUS wire is times 20. All power delivery is is running the VBUS wire at 20V instead of 5V and the sideband protocol to agree on boosting the voltage and finding out what the max voltage and current of the source is. Thunderbolt requires the fastest of the differential lane configurations and if you get thunderbolt + PD, you know the max VBUS current of the cable.
  - edude03 4y ago
    Yes, but for people thinking of going down this path, the cables are $120 and pretty thick so it’s not without trade offs
    - Teknoman117 4y ago
      Not really. $120 for the Apple branded two meter cable for sure, but the third party ones run about $30/meter. I bought a handful of the one meter "Cable Matters Thunderbolt 4 40 Gbps" cables off Amazon for $30 each. I run one from a Dell XPS 15 laptop pulling up to 100W to a dock. They are quite chunky though. Beware anything longer than 2 meters that isn't an active cable though. The differential lanes will probably drop to 10 Gbps. Fine for USB 3, 3.1, and 3.2x2 but you'll lose half the USB4 bandwidth. --- I'm not sure if Thunderbolt allows for lane speed degradation. You see some "thunderbolt 3 20gbps" cables but I don't know if that's two pairs at 10 Gbps or one pair at 20 Gbps. Now you've got this whole USB4 mess - USB 4 and Thunderbolt 4 are the exact same protocol and physical layer, same controllers and everything. The difference is whether the device or host adheres to the performance specification and paid for certification.

theodric 4y ago

Until some bright spark had the idea to make Thunderbolt 3 share a connector with USB-C. And then Apple (inter alia) released laptops that were either USB-C+Thunderbolt 3 -or- purely USB-C (12" MacBook), making life complicated for folks doing IT support in mixed environments. It Just Works, Unless It Doesn't™

lostlogin 4y ago
Ah, you too enjoy the dongle lifestyle. Apple seems to be moving things forward, where others still keep some seriously legacy options, but neither option is pain free.
eigen 4y ago
hasn't this always happened with internal connectors? SATA rev 1 (1.5Gbps, 2003) used the same connector as SATA rev2 (3Gbps, 2004) & SATA rev 3 (6Gbps, 2009) so drives and motherboards plugged together and operated but at the slowest common speed between them. is USB-C somehow different that people expect Thunderbolt 3 (Dec 2015) using a connector introduced in Aug 2014 on a 12" Macbook announced in March 2015?
- izacus 4y ago
  No, this was always an issue, even in times when you enjoyed yourself with incompatibilities between different RS-232 implementation, VGA cables, DVI digital/analogue mess, FireWire burning out ports and more. The world where a plug was enough to identify underlying protocol in 100% of never fail cases never existed. However, nostalgia deletes enough memory for us to whine about times that never existed ;)

oakwhiz 4y ago

I've been having mechanical problems with M.2. Not only does it specify very thin PCBs for no good reason, but variable length, width, and different fasteners make M.2 a rather annoying form factor for me personally. In addition to problems caused by thermal characteristics or vertical depth used up by heatsinks. It's not always possible to locate a fastener that will work in a given board, or even remove it from the top side without completely disassembling a machine. Not all boards are x86 PCs or servers either, M.2 is now used in embedded devices and some assumptions can't be taken for granted there. If you look at PCI or PCI Express there is a mechanical component to the case and socket which holds on to the card so that it's not just floating there. However M.2 capable boards seem to have a wide variety of fasteners, and that's the only thing holding it in. There is no standard part for this, and good luck if you need a replacement or it wasn't included in the stock machine. I've also watched an employee of a computer store install an M.2 card in a bent position because the included fasteners were not even capable of correctly holding the card. Why is it so easy to mis-install in the first place?

wumpus 4y ago

I'm a guilty party for reusing a connector because it already existed -- we wanted to make a HyperTransport slot standard (HTX), so we used 2 PCIe standard connectors. We placed them at an unusual depth from the edge so it was unlikely that anyone would accidentally plug an actual PCIe card into them. But I'm sure someone was confused by it at some point.

nsxwolf 4y ago

I got this NVMe wifi card that uses some key that basically only exists for motherboards and laptops with special NVMe wifi card slots. I couldn’t use it or find an adapter.