I am looking for a graphics card that would be used in a desktop pc running GNU/Linux used mainly for coding. I won't run any games that would require high performance, but I want the card to support three 1920x1080 monitors via digital ports. Nice to have: ability to run OpenCL/CUDA on this card. So what is the cheapest way to meet these requirements?
Now, like others have said, most newer cards are going to meet your criteria, and using PCpartpicker you can select cards that have 3 display ports. So if my suggestion doesn't fit your bill, you should be able to find what you're looking for fairly quick.