Not all OCuLink eGPU docks are created equal

Sep 29, 2025

I recently tried using the Minisforum DEG1 GPU Dock with a Raspberry Pi 500+, using an M.2 to OCuLink adapter, and this chenyang SFF-8611 Cable.

After figuring out there's a power button on the DEG1 (which needs to be turned on), and after fiddling around with the switches on the PCB (hidden under the large metal plate on the bottom; TGX to OFF was the most important setting), I was able to get the Raspberry Pi's PCIe bus to at least tell the graphics card installed in the eGPU dock to spin up its fans and initialize.

But I wasn't able to get any output from the card (using this Linux kernel patch), and lspci did not show it. (Nor were there any logs showing errors in dmesg).

Pi 500+ JMT eGPU Dock Setup

I switched back to my JMT eGPU OCuLink dock for the rest of my testing, and uploaded a video detailing some of my struggles, and a blog post detailing the Pi 500+ eGPU testing.

A few commenters mentioned they too had issues with the Minisforum DEG1. But a few of them looked closely at the OCuLink cable Minisforum included, and noted there were a couple extra colored wires going through the cable sleeve that didn't seem to be present on other cables—like the chenyang I was using! They suggested I try swapping cables.

So I did... and testing it with an RX 6500 XT worked!

Minisforum dock working with AMD RX 6500 XT eGPU on Raspberry Pi 500+

Looking closely at the cables side by side, I can confirm what some of the commenters said: the cable that came with the DEG1 looks like it has additional colored wires going between the connectors.

OCuLink cable that came with Minisforum DEG1

Moral of the this portion of the story: not all OCuLink cables are created equal.

Going Deeper

But then I swapped back to my RX 7900 XT, the one that was previously unrecognized in the Miniforum dock... and it still wouldn't work.

$ lspci
0002:00:00.0 PCI bridge: Broadcom Inc. and subsidiaries BCM2712 PCIe Bridge (rev 30)
0002:01:00.0 Ethernet controller: Raspberry Pi Ltd RP1 PCIe 2.0 South Bridge

I tried all three switches in different settings, I tried swapping OCuLink cables back and forth again... nothing. The RX 6500 XT was happy as can be, but the 7900? Nope.

I even popped in an Intel B580 card, and it worked too...

$ lspci
0001:00:00.0 PCI bridge: Broadcom Inc. and subsidiaries BCM2712 PCIe Bridge (rev 30)
0001:01:00.0 PCI bridge: Intel Corporation Device e2ff (rev 01)
0001:02:01.0 PCI bridge: Intel Corporation Device e2f0
0001:02:02.0 PCI bridge: Intel Corporation Device e2f1
0001:03:00.0 VGA compatible controller: Intel Corporation Battlemage G21 [Arc B580]
0001:04:00.0 Audio device: Intel Corporation Device e2f7
0002:00:00.0 PCI bridge: Broadcom Inc. and subsidiaries BCM2712 PCIe Bridge (rev 30)
0002:01:00.0 Ethernet controller: Raspberry Pi Ltd RP1 PCIe 2.0 South Bridge

So now I'm left scratching my head: what's different about the RX 7900 XT? And why does my cheaper $50 eGPU dock seem to work with everything, but the $99 Minisforum DEG1 doesn't?

Searching through forum posts, I even found someone running a 7900 XT in the DEG1 on a Pi, so maybe it's just a strange fluke with my setup?

Inconsistencies like these really bother me. And they usually eat up an entire afternoon, because I'm always certain it's a PEBKAC, and I usually exhaust every route debugging before I'd waste a vendor or a maintainer's time with a bug report!

OCuLink cable dimensions and pinout from Amphenol

I haven't yet torn down one of these cables to try to figure out which pins are perhaps missing on the chenyang cable (see OCuLink Pinouts here. The bigger issue there is, I can't find a source for the cable Minisforum includes separate from the DEG1 dock, and most online listings don't clearly show which kind of cable you'll get—with or without the extra wires!

Update - Oct 2025

After publishing this blog post, X user @changeforabuttn pointed out a successful test of the RX 7900 XT with a PCIe ReDriver built into the Micro SATA M.2 to OCuLink adapter:

@changeforabutton graciously sent me an adapter to test (apparently the thing's out of stock everywhere right now), and I can confirm it gets all the troublesome cards working on the DEG1. So I guess... with the right PCIe adapter setup, a DEG1 is still a valid choice.

I think for critical work, I'll stick with my JMT dock, but for convenience and large-card physical stability, I'll start using the DEG1 with the ReDriver adapter. Hopefully I can find another option, because most of the M.2 adapters are just straight pin-to-pin without active electronics (which degrades the PCIe link quality).

Further reading: