Steam Link grabs your Nvidia card for VR streaming, and you cannot tell it not to
Steam Link picks a discrete GPU when it streams VR to a headset, and on a machine holding two of them it prefers an Nvidia card over an AMD one. Valve set that order out on September 26, and said there is no option to override it, only a task it will look into.
Steam Link is the path a Steam Frame uses to stream VR from a PC. Image: Valve
The behaviour surfaced in a report from an owner on Fedora 44 whose display card is a Radeon RX 7800 XT, with an RTX 3070 Ti in the same machine purely for NVENC encoding. Their log shows the link starting up on "NVIDIA GeForce RTX 3070 Ti" without appearing to query the Radeon at all.
On that machine the desktop streamed into the headset as a black screen, so did the host Steam window, and No Man's Sky loaded the SteamVR environment and then never rendered into the headset. Half-Life: Alyx ran normally, which is the owner's account rather than anything Valve has confirmed.
Valve says discrete first, then Nvidia
Steam Link by default will choose a discrete GPU, then will prefer a nvidia card over amd which matches the behavior you're seeing.
We don't currently have the option to prefer a specific GPU, but will add this as a task to look into. Thanks.
A card bought for encoding is therefore the card Steam Link reaches for, whether or not it is the one driving the display. An Nvidia card kept purely for NVENC is a common arrangement among people who stream, because the encoder takes the compression work off the card drawing the game.
The owner's own way round it was DRI_PRIME, the Linux setting that pins a program to a named graphics device, written into SteamVR's launch options against the Radeon's address. That is one owner's workaround rather than guidance from Valve.
A hybrid laptop is a different case entirely
SteamVR's 2.18.1 beta does fix GPU selection on Linux systems that carry both a discrete and an integrated GPU. Two discrete cards is not that case, and nothing establishes how the pairing behaves on a Windows host or on any particular laptop; the hope that a picker would help gaming laptops came from the owner, not from Valve.
Nothing establishes how many machines are wired up this way either. What Valve has confirmed is the rule the software follows, and that overriding it is not supported.
Steam Link's defaults have been moving all month
Valve turned the new sharpening filter off by default in SteamVR 2.17.10, and added an experimental codec called Pyrowave to the Steam beta client, which pushes bandwidth up to ten times higher and wants gigabit ethernet behind it.
For now a PC with an AMD display card and an Nvidia encoder gets Valve's order of preference and nothing else. The owner who reported it asked for a picker, and Valve wrote the request down.
