Indie dev reverse-engineers Asus proprietary XG eGPU connector to work with unsupported devices — open-source GPU docking station embraces ROG Ally and ROG Flow

Official render of the Asus XG Station Pro eGPU Dock, produced in collaboration with InWin in 2018.
Official render of the Asus XG Station Pro eGPU Dock, produced in collaboration with InWin in 2018. (Image credit: Asus)

Yesterday on Twitter, noted independent open source developer DontStealMacOSY released his own XG_Mobile_Station documentation on GitHub. The documentation includes a detailed run-through of how he reverse-engineered Asus' XG Mobile connector to create an open-source GPU docking station for Asus ROG Ally and ROG Flow—or as a drop-in upgrade for the original XG Station Pro, which didn't have an XG port.

Among eGPU docking solutions, there is an understood pecking order at which basic USB plummets to the bottom, and solutions like the high-bandwidth, low-latency OCuLink dominate over even Thunderbolt— but proprietary solutions like Asus' XG Mobile interface also tend to be quite performant. With some devices, eGPUs are best used (or only used) with those proprietary solutions. In the case of the two recent Asus devices this is targeted at, the ROG Ally and the ROG Flow, it's worth noting that neither device supports the faster OCuLink connector (~16 GB/s) but does support the proprietary XG connector (~8 GB/s), which approximates PCIe Gen 3 at x8 lanes for ROG Flow and just x4 lanes for ROG Ally.

According to the official development diary posted by Osy on GitHub, this project was inspired by the discovery of ROG Flow X13 schematics, which gave a pinout listing of the XG Mobile connector and the existence of the cable itself for individual sale from Asus. Using the information available, Osy could find the origin of the three proprietary board connectors (one 8-Pin, two 40-Pin) and confirm that each part needed to make one's own XG Mobile cable, which was freely available for purchase.

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Christopher Harper
Contributing Writer

Christopher Harper has been a successful freelance tech writer specializing in PC hardware and gaming since 2015, and ghostwrote for various B2B clients in High School before that. Outside of work, Christopher is best known to friends and rivals as an active competitive player in various eSports (particularly fighting games and arena shooters) and a purveyor of music ranging from Jimi Hendrix to Killer Mike to the Sonic Adventure 2 soundtrack.

  • kealii123
    As cool as this is (kudos to the tinkerer), it needs to go the other way. The best eGPU solution out there right now is Asus's XG Mobile RTX 4090, an eGPU the size of a small book that has the same performance as a desktop RTX 4080 for most applications. Allow me to plug that into a thin and light laptop or handheld via an M.2 adapter or occulink and now we are talking.

    The GPD X1 and the onexplayer's eGPU are both pretty compact and cool, but they use an underpowered, mid tier AMD laptop GPU thats barely ahead of a laptop RTX 4060
    Reply
  • thestryker
    Given that Asus has dumped the connector on the new Ally it's probably a good thing this has been done. I'm not sure Asus has put the XG port on any of their 2024 models which may indicate it's on the way out. The pricing on their proprietary docks has been absurd so I can't imagine the volume has been high enough to justify continued investment.
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