Resolve's GPU Processing Mode menu offers Auto, Metal, OpenCL and CUDA - and picking wrong is behind half the GPU warnings on the internet. Here is what each one actually is, in plain language.
A GPU processing mode is simply the language Resolve uses to talk to your graphics card. Each graphics platform has its own native language, and Resolve speaks all three - but it works best when it talks to your card in the card's own tongue. The warning appears when Resolve ends up speaking the wrong language: most often it wanted CUDA or Metal, failed, and quietly fell back to OpenCL. Understanding the three modes takes five minutes and permanently demystifies that settings page.
CUDA is NVIDIA's computing platform, available only on NVIDIA GeForce and workstation cards. It is the deepest, most direct path between Resolve and an NVIDIA GPU, and the one Blackmagic optimises hardest for on Windows and Linux. If your machine has an NVIDIA card, CUDA is the mode you want to see selected - full stop. Resolve asking for CUDA and failing is never a mode problem; it is a driver problem, because CUDA is delivered as part of the NVIDIA driver.
Metal is Apple's graphics and compute framework, and it is the only high-performance path on a modern Mac - Apple silicon machines and Intel Macs with AMD cards alike. On macOS, choose Metal (or leave Auto, which correctly lands on Metal). Macs are also where the classic wording of this warning comes from: Resolve announcing it is using OpenCL instead of Metal means something - an old macOS, an old card - blocked the Metal path.
OpenCL is the open, cross-vendor standard. It works on AMD cards on Windows and Linux (where it is the correct, intended mode - not a fallback), on Intel graphics, and historically on Macs. OpenCL itself is not slow or broken; on an AMD Windows machine it is exactly right. It only signals trouble on NVIDIA and Mac systems, where its appearance means the preferred native path failed and Resolve took the universal translator instead.
There is no performance prize for experimenting beyond this table. A card cannot speak a language it was not built for - an AMD card will never offer CUDA, and forcing the menu toward it only manufactures errors.
The video walks the Memory and GPU page mode by mode - watch it once and the Auto, CUDA, OpenCL and Metal options will never look mysterious again.
▶️ Watch Full VideoOn the same NVIDIA card, yes, generally - CUDA is the native, optimised path. But the comparison only exists on NVIDIA hardware. On an AMD card under Windows, OpenCL is the native path and performs as designed; there is no CUDA option to be slower than.
Because the CUDA path failed to initialise - almost always a driver that is too old or damaged. Resolve prefers to open in a reduced mode rather than not open at all, and uses the warning to tell you it did so.
Yes - the moment a GPU warning appears, or when Resolve has picked the wrong GPU on a dual-GPU machine. Auto is a good default on a healthy system and a bad one on a system you are troubleshooting, because it hides which choice Resolve actually made.