Do you have the latest GPUs.txt file downloaded by the client and in place? If so the GPU should show up as supported in the log file kept by the client. If not recognized there, a restart of the FAHClient process would be needed after the GPUs.txt file is updated and current drivers installed.
If the GPU is recognized, then it is probably a different issue. Could you post the first 100 or so lines of your log file showing the system info and folding configuration the client sees. If there are some error messages, include those as well. Directions on locating and posting the log file are included in the Welcome topic - viewtopic.php?f=83&t=26036