- SET CUDA_VISIBLE_DEVICES="1,2,3"

[luky76]

WHY this command not select those GPUS?

[quydau35]

Actually this features is not developed yet. You can only set your specific GPU device by hard code changing line 461 in secp256k1/src/autolykos.cu from
for (int i = 0; i < deviceCount; ++i)
to
for (int i = 0; i < deviceCount - 1; ++i)
to the amount of devices you wanna use (for me it is deviceCount - 1 because I want to omit one of my card). And try to compile the source code on your own.
I did it successfully.