In context: Valve's Steam Deck wasn't designed to be a PC gaming beast, but that hasn't stopped people from testing how far it can go with some augmentations to its capabilities. For example, you can attach an RX 6900 XT for a sizable boost to overall performance. It will be interesting to see if Valve will decide to add official eGPU support to Steam Deck's eventual successor.
The Steam Deck is a desktop computer at heart and a handheld console in practice. Earlier this month, its BIOS was updated with fTPM support to allow users to install Windows 11. Microsoft's new operating system has some strict system requirements that have less to do with CPU or GPU power and more to do with hardware security features the company now wants to fully utilize on consumer hardware and enterprise machines.
The performance of the Steam Deck is adequate for its relatively low-resolution screen. However, YouTuber ETA Prime has decided to take things up several notches and jury-rig a fat desktop GPU to Valve's handheld console. The device doesn't have a Thunderbolt port for connecting an external GPU, so to do this, he used an adapter connected to the M.2 slot.
The disadvantage is that the OS and games have to run from the slower microSD storage. Furthermore, the Steam Deck won't boot if you attach an Nvidia GPU to it but will happily work with AMD Radeon cards such as the RX 6900 XT, which ETA Prime used in the experiment.
As you'd expect, the Steam Deck's low-power APU struggles to feed a monster GPU like the RX 6900 XT, especially through the limited PCIe lanes of the M.2 slot. Still, the contraption scored almost 27,000 points in the 3DMark Fire Strike test and over 15,000 in the TimeSpy benchmark.
For reference, that's between 5 to 10 times faster than with the Steam Deck's iGPU. Gaming tests revealed a similar story, with the RX 6900 XT enabling the handheld console to achieve well over 60 frames per second at 4K in titles like The Witcher 3 and GTA 5 using the maximum graphics settings. The same wasn't possible in recent titles like Cyberpunk 2077 and Elden Ring, in which the setup struggled to output a constant 60 framers per second even at 1080p, mainly because of the relatively weak CPU.
Of course, most users can achieve better results by using a cloud gaming service like Microsoft's Xbox Cloud Gaming, provided you can get it to work correctly on the Steam Deck. In the meantime, Valve and AMD are still working on proper driver support for Windows 11 and making enough Steam Deck units to satisfy the higher-than-expected demand from gamers.