One of the cooler applications of Thunderbolt is the ability to connect external GPUs. However, you lose a lot of performance that way because PCI Express has to be wrapped in Thunderbolt, and that's inefficient. You get better performance if you simply run a wire for a direct PCI Express connection, which is exactly what the OCuLink standard is for, but you really don't see that on consumer hardware much. Well, thanks to the modularity and open-source nature of Framework laptops, an enterprising user has added an eight-lane OCuLink connector to his Framework Laptop 16.
Framework asked its customers way back in June of 2023 if they would be interested in an expansion bay module for the Framework 16. That machine includes a PCI Express x8 connection that can be used for upgradeable high-performance graphics or storage with an appropriate module. Framework's founder and CEO, Nirav Patel, said at that time that a mostly passive adapter board to connect the Framework motherboard's PCI Express x8 connector to an external OCuLink port "is probably possible," but that it "probably isn't something that [Framework] would build," largely due to how niche a product it is.
Now, OCuLink isn't some obscure proprietary connection. It was created by PCI-SIG — you know, the guys who create PCI Express standards — and intended for use in big servers, which is why we never really saw it in consumer hardware. There's a newer standard called CopprLink that supersedes OCuLink, but it's not meaningfully backward compatible, which is to say that it uses different connectors and cabling standards. OCuLink was officially deprecated in 2021, as the working group for it dissolved then. The standard doesn't simply go away, though, and neither do all the cables and connectors that were manufactured for it.
OCuLink is preferable for eGPUs used for gaming because it offers real advantages over Thunderbolt. Not only does it offer superior bandwidth and latency characteristics — both important for real-time graphics — but it is also drastically simpler to implement. You miss out on hot-pluggability as well as integrated transport for USB, audio, and video, but those are the trade-offs you have to make for a connection that can be implemented by hobbyists working with hobbyist-grade tools.
While OCuLink is still extremely niche, more recently, we've started to see device vendors out of China feature the connection; primarily, mini-PC sellers like Minisforum and GMKTec, as well as handheld makers like GamePad Digital, Ayaneo, and OneXPlayer, have all started adding OCuLink to their devices specifically for the purpose of connecting powerful external graphics cards. That's exactly what Filip did here with a desktop-class GeForce RTX 4070 card. He hasn't presented any footage of the laptop and its external GPU running a game yet, but it hasn't even been 24 hours since he posted about his success.
Framework itself is now assisting in the effort to make this product functional for its users; the company's Device Software director, Kieran Levin, posted in the thread about two updates that he pushed to improve Framework's firmware tools. Perhaps most critically for DIY-minded Framework users, Filip (who goes by "Terrails" on GitHub) has posted the full schematics on his repository, which you can find here.
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