Since BOINC does not allow moving the disk space after install, I moved it during all tasks suspended and boinc manager exited by copying the directory to a bigger drive and putting a symbolic link in its place to that directory. When I restarted BOINC Manager, the old disk size is still in control.

Of course, this is a side effect of not having configuration control of the DISK space and other install parameters as a configuration tool, even if it requires reset of all active projects.

Oops. I moved .BOINC, not /var/lib/boinc-client (why is boinc data a lib?) Now it is adjusted correctly.

I also moved the data dir /var/lib/boinc-client to my secondary HD and replaced it with a link and reinstalled boinc, rebooted, and now the GPU is not included and the disk size is OK, so not just moving the dir.

Prior to installation, you can set up /var/lib/boinc-client as its own partition if you want it on a different disk etc.