I'm using a Nvidia GeForce 720 display adapter that supports OpenCl but I can't get Painter 2020 to use it. It appears the accelerator application recognizes it. How do I get painter to use it?
The Painter Brush Accelerator test compares the performance of your GPU to your CPU and determines what are the optimal settings for your system.
The most important thing when running this test is to ensure you do not have extra documents or applications open, as they can affect the test results. (so if you did have extra docs and apps running, consider closing those and re-running again)
After the test is run, the optimal settings are chosen: In some cases, the GPU is very strong and will create a noticeable improvement in brush performance--the cylinder will turn green. In other cases, your CPU may be very strong...so strong in fact, that it is the better device to use for all painting activities. In these scenarios you will see a greyed out cylinder because the GPU will not be used.
I suspect in your case, you CPU is stronger than your video card for brushing duties.
On my personal Painter systems:
System A: Has a GeForce 1050ti with a 2nd Gen Intel i5 processor. Cylinder is green, GPU is used.
System B: Has a Radeon R9M370x with a newer AVX2-compatible 2.5gz i7 processor. Cylinder is greyed out, GPU is not used.
For the record, both systems paint quite fast with Painter 2020, and paint faster than Painter 2019.
I hope this helps clarify...
In my case the GPU tower shows that it supports OpenCL 1.2 but noted it was not in use but is recommended as indicated in the picture I posted above.