Consumer GPU in 3U rack case

Hackerspace Computer Projects
#1

I’m trying to move my GPU compute nodes into a rack. Bought a couple Supermicro 3U cases, put everything in (including 1080 TIs), wired it up…and the cover doesn’t fit. The power plugs on Nvidia’s consumer GPUs point up - between the plug and the bend radius of the cables, it’s adding close to an inch. Unfortunately, the 3U case has less than half an inch of clearance.

I’ve seen people referencing direct connecting the wires on forums, but haven’t seen any pictures or details on how they’ve done it. Seeing low clearance plugs available online, but they don’t change the direction of the wires, just cut 1/4 inch off the plug - I might be able to jam them in, but doesn’t seem like a great option. Conceptually, an adapter that moved the plug to the back of the GPU seems straightforward (plug just high enough to hold connectors, bend/solder connectors 90°, align cables like a ribbon, female connector at the back), but I haven’t seen it done.

Anyone run into this? Thoughts?

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#2

Do you think something like this might be too thick?

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#3

you can pull the pins out of the molex enclosures and wire directly into the socket.

I used SL250 blade chassis to make our rackmount compute systems, since they’re designed for GPUs. On the right side blades we ran into a similar issue and trimmed the chassis a little to make it work.

I think we still have some decommissioned units that might be for sale.

However, as for a technical solution if de-pinning the cables isn’t successful there are a few options besides new chassis. You could try to outfitting right angle connections however I don’t recall how much room there is on the PCB on 1080 cards since some of them have the oversized enclosures.

Do you have reference cards or ones with custom heatsinks?

#4

All reference cards. I chose the chassis b/c they 1) accept my existing EATX and SSI CEB mobos w/o modification 2) can fit 3 in my 15U rack 3) have 8x3.5" hot-swap bays 4) have room the GPUs. I thought about de-pinning the cables, but was concerned about them staying in place and having to keep track of wiring order would be annoying. Now that I’m typing this, realizing movement is probably a non-issue…there isn’t enough clearance for them to pop off. I probably should have just gotten a larger rack (somewhere in the 20-30U range) and gone w/ 4U chassis.

What type of right-angle connectors are you referring to?

#5

That’s too thick - needs to be 1/4", maybe 3/8". The design I had in mind was just like that, but keeping the top under 1/4" - any reason that wouldn’t be possible?

#6

You could always layout a PCB and do it yourself. The Molex connectors they use are technically purchasable through places like Mouser, and you can get the the PCB height down to really thin (1.6mm is the default thickness). Were it me, I would either make a custom wire harness to power them up (de-solder the connector from the card or solder to them directly), get a different case, or get different cards in order of most to least difficult.

#7

Ordered the parts on mouser (sidenote - holy eff finding the parts was brutal). I’ll post pics if it ends up working.

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#8

Check one last time that the keying pins are either swappable or are in the right place. Yeah, Mouser can be a pain to find the right part, but honestly, I think they are the least bad out of the alternatives.

Also, you’re close enough, you should get your parts next day.

#9

You can pick them up on Will-Call if you like. I don’t like being charged 10$ for shipping. Same thing at Allied Electronics.

#10

Removing the connector and going straight to the board with the power wires is an option. That adapter is a much more elegant solution. Just saying there are others that are… Less elegant.

#11

Good to know, didn’t notice that option when checking out.

#12

Mouser’s site is as good as I could hope for…once you know which part you want. Difficulty was determining the sockets - Molex doesn’t say “this is the standard socket for x” (there are about a hundred options that do the same thing w/ tiny variations in size/mechanism for staying in place/etc). Guessing the PCI specifications would list that sort of thing, but couldn’t find them free online (Makerspace happen to have copies laying around somewhere?).

Although removing the connector, soldering in an extension would work well, I’d prefer not to void the warranties…

My plan is for a ~6" extension with a low clearance plug, wires coming out parallel to the card - cut down plug as much as possible (such that the female sockets remain in place), insulate sockets w/ electric tape, bend 90°, align wires like a ribbon, normal connector on other side. I thought about soldering the sockets to metal rails (like a static, low clearance version of the EVGA adapter), but seems like more work up front - if I was designing for mass production, I’d probably go that route.

What is your idea w/ a PCB? I’m not following…

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#13

I was saying if you couldn’t find wire-connector options, designing a PCB for connector to board and wire to board would be possible. If you found the right connectors for connector to wire then you’re in good shape.

#14

Here is how I installed an EVGA RTX-2070 in a 3U rack mount case.
http://www.moondew.com/gpu3u/index.htm

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#15

SMC’s reference architecture for running GPUs is to put them on a riser card, not on the PCI-E slots on the board.

If you give me a motherboard reference number, I can give you the part number you need for the riser card.

Additionally, for the future, this allows you to put 2 GPUs into a 2U form factor.

#16

https://www.newegg.com/Product/Product.aspx?Item=9SIAHFV8J01503

PCI-E x16 3.0 Black Extender Riser Cable 200mm