With an externally connected Radeon RX 6900 XT, a Youtuber wanted to improve the performance of the Steam Deck.
An external graphics card can significantly increase the performance of the Steam Deck.
The performance of the Steam Deck handheld PC is sufficient for most current PC games. By reducing the details or refresh rate, you can squeeze a little more runtime out of the relatively small battery. However, the Youtuber ETA Prime did not want to be satisfied with the AMD graphics unit integrated in the Steam Deck: With the additional performance of a Radeon RX 6900 XT, he also wanted to play current games in 4K resolution and with 60 frames per second on a connected monitor or television .
Connection via M.2 slot
The external graphics card was connected via the Steam Deck’s M.2 slot using an appropriate adapter. However, a direct connection via the USB-C port was not possible because the Steam Deck does not accept Thunderbolt connections. However, it is not possible to connect an Nvidia graphics card externally to the Steam Deck. In order to be able to supply the Radeon RX 6900 XT with sufficient power, the Youtuber used a 750 watt power supply. Actually, a power supply with 300 watts would have been sufficient for this graphics card. Windows 11 was used as the operating system for the experiments, which starts from an inserted SD card.
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CPU as a bottleneck
The connection of an external graphics card to the Steam Deck actually brought the desired effect: “The Witcher 3” ran in 4K resolution with high details at 108 frames per second. “GTA 5” achieved 74 frames per second in 4K. But the system already shows its limits in the role-playing game “Elden Ring”. Even at 1080p resolution, only 46 fps are achieved with maximum details. Interestingly, if you increase the resolution to 4K, only 4 fps less are achieved. Apparently there is a bottleneck in the Steam Deck’s processor, which becomes a system brake even with a powerful graphics card. Another reason is the M.2 connection, which cannot access the full performance of an external graphics card.
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