U.2 to PCIe Low profile adapter

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compuwizz

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Feb 25, 2017
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I want to use U.2 drives in a 2U server that doesn't have full height slots or an NVMe backplane.

I've seen what looks like full height U.2 to PCIe adapters for drives and physically there seems to be the ability for a half height/low profile adapter to be made but I haven't found one. Does one exist?
 

NateS

Active Member
Apr 19, 2021
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Sacramento, CA, US
There's really not enough room physically though -- keep in mind that you're measuring not from the bottom of the bracket, but from the top of the motherboard slot. The usable space is only 2.536". While yes, technically, that's more than a 2.5" U.2 drive, the remaining 0.036" is not really enough space to route the traces properly and hold the capacitors and whatnot. Even if it's not completely impossible, it'd require a much more complicated multi layer board design, and I imagine most manufacturers decided that extra cost probably isn't worth it for a somewhat niche product.
 

compuwizz

Member
Feb 25, 2017
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Thanks, I was hoping I overlooked an option. U.2 drives are a lot easier to find than AIC.
 

NateS

Active Member
Apr 19, 2021
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Sacramento, CA, US
Keep in mind that if your system has anywhere you can stick a 2.5" drive that's not already wired into a backplane, you can run a cable back to a PCIe or M.2 slot instead of using the kind of adapter that puts the drive in the slot directly.

For example,
Cable: https://www.amazon.com/Cable-Matters-Internal-SFF-8643-SFF-8639/dp/B0716K357W/
PCIe adapter: https://www.amazon.com/U-2-M-2-Adapter-Interface-Drive/dp/B01K1JSNLC/
M.2 adapter: https://www.amazon.com/U-2-M-2-Adapter-Interface-Drive/dp/B073WGN61Y/
 
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nexox

Active Member
May 3, 2023
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There's just not physically enough space, the 2.5 in the name of the form factor is the diameter of the platter that mechanical drives use, the drive itself is 2.75" wide. You need an adapter with a cable and remote mount and power or a different form factor.
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mattventura

Active Member
Nov 9, 2022
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anyone figured this out yet?
No, there simply isn't enough height in a LP slot to fit a drive. Take a 2U LP chassis, and place a 2.5" drive on top of a PCIe slot. The drive will stick out the top of the chassis.
 
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ano

Well-Known Member
Nov 7, 2022
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No, there simply isn't enough height in a LP slot to fit a drive. Take a 2U LP chassis, and place a 2.5" drive on top of a PCIe slot. The drive will stick out the top of the chassis.
was hopeing someone had made an offsett mount using som space between the pcie slots, need to do a testfit if that is even possible ;)
 

nexox

Active Member
May 3, 2023
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Maybe with a 7mm thick U.2, I am pretty sure the more common 15mm won't fit between PCIe slots. You can, of course, get E1.S adapters that should fit fine if you aren't into that whole M.2 thing.
 

ano

Well-Known Member
Nov 7, 2022
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e1.s stuff is on order, I just had some u.2 drives which would work out ;)

some m.2 stuff on order as well, wonder if quad adapters 22110.. on gen4 works. found one for low profile, have some chassis with limited number of pcie slots, so need large drives, or many