Introduction¶
- The new m.2 PCIe SSDs are similar in price to SATA SSDs and much faster.
- Most 1U server mainboards have multiple PCIe connectors, but usually only 1 physical PCIe slot, using a right angle riser card (some proprietary boards can have as many as 3).
- Several adapter designs exist for plugging in an m.2 2280 PCIe card to a PCIe slot, but all are low/full profile in size.
- Since the drives talk PCIe, the adapter are fairly simple, mainly just routing.
- Most PCIe SSDs are PCIe 3.0 x4
What if we could make an adapter that would allow for plugging in multiple adapters into slots on a 1U server?
Physical Standards¶
PCI slot max width 15.24mm (0.6")
PCI Low profile max card height 64.41mm (2.536")
PCI full height max card height 107mm (4.2")
en.wikipedia.org/wiki/Conventional_PCI#...
PCIe card socket height 10.8mm
m.2 max width of card 22mm
en.wikipedia.org/wiki/M.2#Form_factors_...
m.2 socket
www.digikey.com/en/product-highlight/j/...
21.9mm (card PCB is wider than socket)
1U rack unit, 44.45mm (1.75")
1U server, less than that
mainboard normally mounted with 8mm standoffs (I think)
sheet metal thickness for the bottom of case, 1-2mm?
probably adapter+m.2 card should be no taller than 30mm?
PCIe socket (~11mm) + m.2 socket (22mm) are more than that
I need to measure some systems
Design ideas¶
- Try to fit within the standard PCI width of 15.24mm and the 1U height working room. Adapter would be vertical PCB, with m.2 socket that holds m.2 card vertically. Similar to this one but shorter. Also this small one exists but needs to change orientation to fit 1U. This is the shortest one I’ve found.
- Violate the PCI spec and make an adapter that the board and card are at an angle (similar to old tall memory module mounting.
- Violate the PCI spec and make an adapter that the board and card are at a 90 degree angle, consuming space outside their slot. Possibly you could make one “short” design and one “tall” and you could stagger them in the slots so as to not interfere
- some other design that consumes more than a normal slot, but allows you to plugin multiple m.2 cards, using a ribbon connector to connect to a second slot. Like this one
