Question Why are most PCIe 4.0 M2 slots far longer than any existing SSD that would fit in them?

Jun 23, 2019
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Hi,

I am looking online for an explanation for why most of the M2 slots are far too large for any form factor that SSD cards seem to be made in.

I have a Samsung 970 EVO. To my knowledge, it is the largest of 3 SSD form factors at 80 mm long. My motherboard has three M2 slots on it. However, two of them are waaaay to long to house an SSD card; at least with the card being screwed in at all. (My Mobo: https://www.gigabyte.com/Motherboard/X570-AORUS-MASTER-rev-10#kf)

My question is... why? Is it intended that the card just sits there flopping around, unsecured? An SSD is inherently pretty insecure in these slots. It sits at an angle until you push it down and screw it in. It sort of acts... springloaded in the M2 slot. I am unable to find anyone that explains this in any particular detail beyond "yes, all three slots take SSD's", wheras I want to know why 2 of the 3 slots are far too large for any SSD to be placed in them while also screwed down.

Thanks!
 

USAFRet

Titan
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Mar 16, 2013
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2280 is the typical consumer length M.2 drive.
The M.2 spec allows for 110 mm length, and there are some enterprise level 22110 length drives coming online.

Your motherboard should have holes relevant for at least 60 and 80, maybe 42 and 110 mm length drives.
Your 970 should NOT flop around.
 
Reactions: tsibiski
Jun 23, 2019
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Interesting, but there is no docking pillar (like in the shorter M2 slot where the pillar screws in at the 80 mm length.. So I suspect that is what the board's longer screws are for then; longer screw acting as a pillar essentially? Sorry, I scoured the x570 Master's guide, and it gives extremely little information about the usage of the PCI 4.0 M2 ports.
 
The main reason there are several standard lengths for PCIe, M.2 solid state drives is a matter of convenience, flexibility, and expansion. For the most part the 80 mm length is currently the most common length for consumer ssd's. As USAFRet and popatim pointed out, modern motherboards are designed to accommodate all of the standard M.2 lengths.

Intel has been using the longer 110mm length in the M.2 versions of their new Intel 905P and 900P ssd's. At the other extreme, the short lengths are commonly used in small portable pc's and devices.
 

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