Modder adds Radeon RX 9070 XT eGPU to Steam Machine, runs Crimson Desert at over 100 FPS on High — moves boot drive to USB-C port, leverages M.2 to OCuLink adaptor and eGPU dock

The modification replaces the Steam Machine’s internal graphics path with an external Radeon RX 9070 XT by inserting an M.2-to-OCuLink adapter into the only PCIe 4.0 NVMe slot. Because that slot is occupied by the SSD, the boot drive is moved to a USB-C NVMe caddy that connects to the rear USB 3.2 Gen 2 port. The Aoostar EG01 dock provides the PCIe slot and circuitry for the desktop GPU but lacks an integrated power supply, so a separate PSU is required.

Implementing the upgrade costs an M.2-to-OCuLink adapter, the Aoostar EG01 dock, a USB-C NVMe enclosure, and an external power supply. A physical case modification is needed to route the OCuLink cable through the chassis, and the system remains open-frame during testing. The overall setup is bulky and visually unappealing, with the dock and PSU exposed on the desk.

Performance testing shows the eGPU delivering more than 100 FPS in Crimson Desert on the High preset, roughly double the frame rate achieved by the Steam Machine’s native GPU, which is comparable to a Radeon RX 7600. The eGPU is recognized as the primary graphics device automatically, eliminating driver selection steps. This demonstrates a substantial gaming uplift for a compact system that otherwise cannot accommodate a full-size GPU.

The solution is constrained by the Steam Machine’s I/O: the USB 3.2 Gen 2 port provides a maximum of 10 Gbps, which is lower than the bandwidth available on newer USB4 or Thunderbolt links. Consequently, the eGPU may not reach its full PCIe potential, and the lack of a built-in PSU in the dock adds to the power management complexity. Additionally, the single M.2 slot prevents simultaneous use of an internal NVMe drive and the adapter without the external boot drive workaround.

For engineers, this hack illustrates that compact PCs can be retrofitted with high-end GPUs using adapters, but the trade-offs include reduced bandwidth, extra power hardware, and required chassis alterations. The approach is best suited for stationary setups where performance outweighs portability and aesthetics. Future designs would benefit from native USB4/Thunderbolt ports and multiple M.2 slots to simplify such upgrades.