First, check the recovery options for your file type at:
Types of files without a "Yes" in the "GPU Support" column are not supported for GPU acceleration and will be utilizing CPU only.
You can also use a free demo or a full version of Passware Kit to check this out. Run Passware Kit, click Recover File Password and locate your file. The program will display the information in the Complexity field on the top of the window. It will show which approach can be used to recover your file, as well as whether hardware acceleration is applicable.
If you have other issues, please refer to the following Troubleshooting article: https://support.passware.com/hc/en-us/articles/221743488-GPU-acceleration-troubleshooting