It would seem to be physically possible to fit dozens of m.2 slots on a motherboard. Why can't I find a motherboard with more than 3? Surely servers would have a use case for more than 3 m.2 ssds?

  • To people who put this question on hold: This question, to me, is about buying a motherboard with support for numerous M.2 ssd. This is a hardware recommendation so I don't understand how its marked as off-topic. – cybernard Nov 9 '18 at 2:25
  1. The M.2 slot requires and x4 pcie equivalent to have enough bandwidth to function at the expect speed.
  2. The chipset has a limit to how many pcie lanes are physically available.
  3. Some of the lanes are dedicated to other devices.
  4. Physically space requirements as most M.2 lay flat down against the motherboard. each one is approx 22.1 by 80.26 =2.75 square inches if you want a dozen that is 33 square inches. ![24 M.2 ssd The ATX size clearly doesn't allow for a CPU, and squeezing RAM on there would be tricky at best.

EATX probably has enough room for a CPU and maybe RAM, but nothing else. Since the northbridge chipset requires active cooling there is no room for it under the M.2's.

SSI MEB would have enough room and I don't think those are very common.

WTX would have enough room, but I don't know how common they are.

    So screws may secure them into place.

5. You can't place them close to the PCIe slots due to potential pcie card over hang.

Cards like this allow 2 in 1 pcie slot

Silverstone SST-ECM22 Dual M.2 to PCI-E X4 NVMe SSD/SATA 6G Adapter https://www.google.com/aclk?sa=l&ai=DChcSEwiMq7y8hLbeAhWFJmkKHSq4D_4YABAZGgJpcQ&sig=AOD64_3t6MTcwHm1WdEACCQOhozV3m3Kgg&ctype=5&q=&ved=0ahUKEwi-47e8hLbeAhVrw4MKHTKOA2E4ZBDYKQiIAw&adurl=


  • I think the PCIE lane issue is particularly problematic, especially for users who want to have multiple video cards. Granted, typical use will not be saturating the lanes constantly, but even Intel's 9900k only has 16 PCIe lanes, so for a high-end system with 2 video cards and multiple NVMe drives (in PCIe slots) the graphics cards could be forced all the way down to 4x speeds and at that point the performance hit would be really noticeable. – process91 Nov 2 '18 at 22:48
  • @process91 I know it's apples and oranges, but 2nd-gen Threadripper has 60 PCIe lanes, while i9-7900X has 44. – Jan Dorniak Nov 7 '18 at 1:07
  • The B key only needs two PCIe lanes, not that it helps. And well - somehow it's possible to use one x16 or two x8 slots with GPUs... Why wouldn't this work here? – Jan Dorniak Nov 7 '18 at 1:10
  • @JanDorniak only x4 offer 2000mb/s and x2 is only 1000 and m.2 offer 2000 or even 3000mb/s performance depending on the model. The GPU are 2 x16 slots only get x8 bandwidth each, but the physical slots are x16. There are pci express expanders, but they have an x16 or x8 interconnect so if you care about speed these expanders are completely out. If your using M.2 ssd you definitely care about speed. – cybernard Nov 9 '18 at 2:08
  • @cybernard I meant lane reassignment at boot... – Jan Dorniak Nov 9 '18 at 6:57

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