GPU acceleration greyed out on iMac with macOS Mojave (10.14.6)

[kuppj00]

On Photoshop version 22.3.1 and 22.4.0 the GPU acceleration is off and greyed out on my iMac with macOS Mojave (10.14.6).

This is the last version from macOS that works with 32 bit applications. I don't want to upgrade because else my printer/scanner with not work.

On Photoshop 22.3.0 the GPU is working with the build in NVIDIA GeForce GT 750M in my iMac.

I have tried to reset the Photoshop setting but that did not help.

What can I do to make the GPU work in the updated Photoshop versions? 

[davescm · Accepted solution]

There are several things at play here.
1. Adobe are updating the core graphics functions in Photoshop. This is driven by the operating systems of Apple and Microsoft in which the old Open GL functions are being removed in the case of Apple, or deprecated in the case of Microsoft. This means that the graphics functions that have worked for years must be rewritten to use Metal and Direct X. At the same time, Adobe are sensibly updating those core functions to deliver the additional speed we require to handle the very large files of today.
2. Led by the changes being made above, Adobe introduced new GPU checks in 23.3.1. Unfortunately, these caused issues and have therefore been revised for v22.4. That means that many GPUs that incorrectly did not work in 22.3.1 will now be seen in 22.4 and will function.
3. Some functionality in Photoshop, such as 3D, still relies on the older Open GL graphics functions. To make these work, an additional preference Preferences>Technology previews>Deactivate Native Canvas has been added. This can be checked and Photoshop restarted to restore 3D functions to where they were in 22.3
4. Unfortunately, the move to update the core graphics functions will mean that some older GPUs will no longer be suitable. If you are using 22.4 and your GPU is still not recognised (and you only have a single GPU enabled – conflicting GPUs remain an issue) then you could try and force Photoshop to use your older GPU by creating a file PSUserConfig.txt containing the lines:
# Force GPU On
GPUForce 1

Save that text file in :
Windows: [InstallationDrive]:\Users \ [UserName]\ AppData\ Roaming\ Adobe\ [Photoshop_version]\[Photoshop_version]Settings\
macOS: //Users/[UserName]/Library/Preferences/[Photoshop_version]Settings/
Note though that this is not officially supported by Adobe and may cause other issues – so you do it at your own risk

Dave

[kuppj00]

Dave,

Thanks for your great answer.

I have created the PSUserConfig.txt as you told and now the GPU is working again.

Hans