Adding NVMe devices to dell R720 (PCIe switch chips)

tl;dr I’m stuck on old dell r720 and I have U.2 NVMe-s collecting dust.
I’ve found a way to connect them to the system without spending too much money.

Here’s a short howto. you can probably adapt it to other old servers if they have enough free space and you’ll find a free header with 12V.

If you want to do it you’ll need 4 things:

  • PCIe switch card (old servers don’t support bifurcation)
  • SFF 8643 (mini sas hd) to SFF-8639 (u.2) cable (80 cm)
  • dell backplane power cable (0123W8)
  • some U.2 device
  • sacrificial sata extender/splitter

backplane power connectors on dell r720 motherboard:

On this photo cable is already connected. My cable is correctly color coded. Yellow is 12v, black is ground. I haven’t checked gray but some people online claim it’s for backplane sensing.

You have to make solder 12v and ground cables from backplane power to your sata splitter.

My cable

I’ve connected 2 yellow and 2 ground cable to my sata cable just in case. I’ve also later soldered both sata ground cables together, just in case.
This cable has only 12v power but it should be enough for server U.2 drive. You may have problem if you tried to use it with M.2 to U.2 adapters. M.2 drives usually prefer lower voltages (they lack internal power conversion?).

My r720 has only one 8 drive front cage. I’m placing my drives in drive cage blank.
I’ve tested 2 and 4 drive configurations:
2 drives (2 port PCIe switch card)

4 drives (8 port PCIe switch card)

I managed to fit all cables in cable management hole but it’s really tight.

Drives I’ve used:
Intel optane 900P
Samsung PM9A3
Micron 7300 PRO

All drives are detected and connected at full speed supported by PCIe switch.

Maybe I was lucky with drive selection. I have dead U.2 intel p3600 which requires 0,1A of 3.3v. I couldn’t test it. I’m guessing that future of serverland is in 12v.

If you drive needs 5v you can steal if from loose sata power cable around cd drive. (my server has one). If you need 3.3v you may be able to get it from gray cables on backplane power cable. Or form the other backplane cable.

PCIe switch chip cards used.
Linkreal 2 port card (pcie slot x8)
Ceacent 8 port (pcie slot x16)

Last time I’ve checked Ceacent had much better prices. Silicon is the same both vendors use PLX chips.

I’ve also considered cutting front of the empty drive cage blank, drilling few holes for screws and installing IcyDock ToughArmor MB699VP-B… but it costs 380 Euro. That’s insane.

RIP, my pinecil died during this project. It’s the second time I’ve soldered sth with it. (hopefully just the tip is dead)


Interesting. I’m considering getting an NVMe M.2/U.2 server enclosure, so these PCIe switches are very useful for that.

Given I work for a company that actually makes cables (just not for PC/server hardware anymore), that’s not a major issue :wink: Out of interest, where do you need this for? Powering the U.2 drives is the only thing I can think of ATM?

It powers U.2 drives. I take power from the motherboard and use it to power SSDs.

mini sas hd to U.2 cables look have sata power plugs. You can power them from normal sata cables.

I’ll replace 2nd photo with less cropped one. It may be more obvious what’s happening.

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Or you could just have bought the original Dell NVME kit to add 4x U.2 bays to your R720 8SFF. This is how the kit looks like PCIe NVME U.2 SSD SAS CARD EXPANDER DELL POWEREDGE SERVER R720 R820 YPNRC 693W6 | eBay
If you order the same parts separately - it should be about $100 total.

Updated the ebay link. The one I picked originally had the wrong (SAS instead of NVME) backplane pictured.

I didn’t want to waste my money on parts which only work in one obsolete server. I’d rather buy MB699VP-B and jerry-rig it into the server.

I’ve made parts list and it added to something close to the one on that auction. Drive cages I’ve found were too expensive.
I also had spare pcie switches.

I completely undestand your personal preference. But you made it sound like there was no other way. Also MB699VP-B alone is like $350+. With that money I’d rather buy a whole R730xd to replace the R720 instead.

I’d say that r730xd equally as obsolete as r720. (no-one should upgrade to these platforms in 2023)

There are other ways, I just wanted to show example of cost effective one.

MB699VP-B is just an idea for the future. Something I could reuse in my future server build.
For now, just inexpensive u.2 cables.

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