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

A Redditor has successfully connected a very powerful eGPU to the Steam Machine. Large_Customer_3840 briefly explains how they managed to add a potent AMD Radeon RX 9070 XT to Valve’s compact modern gaming desktop by fitting an M.2 to OCuLink adapter in the machine. That was cable-connected to an Aoostar EG01, which hosted the hulking triple-fan desktop graphics card. However, there remained some wrangling to do due to Steam Machine hardware limitations.

The idea outlined above sounds like a quick and simple hack to add a more powerful GPU to the Steam Machine, but there are a few limitations of the Valve hardware that need addressing. Firstly, this compact computer has just one M.2 PCIe 4.0 NVMe slot, which is used by the SSD that Valve supplies with the machine. Valve reckons folks can augment this storage using the microSD slot, just like Steam Deck gamers are accustomed to doing.

So, after fitting an OCuLink to M.2 adapter, Large_Customer_3840 had to find somewhere for the boot drive to live. The answer was simply to shove the boot drive into a USB-C to NVMe caddy and boot from that. Valve’s Steam Machine has a USB 3.2 Gen 2 (10 Gbps) port on the back which supports DP-Alt and Power Delivery. This is the fastest USB port it has, so it was used for the operating system.

A second snag with the M.2 to OCuLink adapter setup here is that there will need to be a case mod done so the cable can be threaded through the rear of the chassis. Large_Customer_3840 hasn’t made such a mod yet, and they are happy to have the system running open for now.

But many eGPU solutions like this, using the Aoostar EG01 in this instance, are inherently messy anyway. This older Aoostar eGPU dock has no enclosure, making it little more than a platform with a PCIe slot and supporting circuitry to host a desktop GPU, exposed, on your desk. Moreover, the EG01 doesn’t have a built-in PSU, unlike some models, so you also have a typically ugly PC power supply in view, too.

Looking beyond the aesthetic mess, the Redditor was pleased that “When I turned it on the 9070xt became the primary monitor and worked straight away. There was no hassle no selecting of graphic adapters.” The extra shot of performance delivered by one of the best graphics cards for PCs in 2026 was also welcomed. Apparently the OCuLink-connected Radeon RX 9070 XT eGPU ran Crimson Desert at over 100 frames per second using the High preset. It would have been interesting to know how the Steam Machine’s built-in discrete GPU handled the game at the same settings… As the Steam Machine basically runs a GPU similar to the Radeon RX 7600 – you can see our extensive Graphics Card Hierarchy data to see the expected difference between the RX 7600 and RX 9070 XT in various gaming scenarios. Online testing for Crimson Desert at the High preset yields frame rates of around 50 FPS, making the eGPU addition a sizeable performance buff.

Many AMD mini PCs come with USB4 ports nowadays, so it is a shame that the Steam Machine’s USB connectivity plateaus at USB 3.2 Gen 2 (10 Gbps) via a single USB-C on the rear. USB4, or better, is a more convenient hot-pluggable eGPU port opening up lots of other docking options for compact system users. It may offer worse bandwidth than OCuLink, but most folks find it an acceptable compromise. I’ve used both and was slightly annoyed by both, vowing not to be tempted into the eGPU world again until mainstream USB4 v2/Thunderbolt 5 solutions have arrived at affordable levels.