Raspberry Pi 5 runs Doom 3 at 4K using an external GPU

WTF?! The Raspberry Pi 5's expanded PCIe functionality is one of its most enticing upgrades over its predecessors. Most owners likely use it to install fast storage, AI chips, or network cards, but modders have successfully connected it to dedicated graphics cards. Although the Pi isn't a gaming PC, installing a GPU on one could unlock interesting possibilities.

Prolific Raspberry Pi modder Jeff Geerling recently published instructions for connecting a Raspberry Pi 5 to an external graphics card. Following years of trial and error, he managed to run Doom 3 at a stable 60 frames per second in 4K.

The project requires plenty of extra hardware and extensive software tweaking. To connect the GPU and convert its signal to the Pi, Geerling used an external graphics card enclosure, an OcuLink cable, a HAT module, an ATX power supply, and a method to power it on.

Testing a few GPUs revealed that older AMD cards suit the Pi the best, due to AMD's policy of publishing open-source drivers, which Geerling could customize for the Pi. The modder chose a 4GB Radeon RX 460 because information on its drivers and hardware is readily available.

After patching the Linux kernel, Geerling chose Doom 3 from a list of games that natively support the Pi's Arm-based system. Id Software's 2004 horror first-person shooter is likely the most demanding game in the pile, but the RX 460 had no trouble running a title that predates its launch by 12 years. Geerling suspects that Doom 3's internal 60fps lock is the only thing stopping performance from climbing higher.

Geerling initially attempted to connect several GPUs to the Raspberry Pi Compute Module 4 in 2022 but only achieved basic graphics display tasks. The Pi 5's PCIe expansion put more demanding workloads within reach. Although it officially only supports PCIe 2.0, unlocking PCIe 3.0 speeds is possible.

Meanwhile, Pineboards successfully ran an open-source racing game on a Pi with an RX 460 in August 2024, prompting Geerling's recent experiment with Doom 3. Looking ahead, the RX 460 likely can't handle AI tasks easily, but video encoding could be a useful application. Geerling is also trying to run web browser engines through the GPU and explore the possibility of making newer AMD cards compatible.