I have Linux Mint 19.3 running on a Ryzen 9 3900X (12 cores/24 threads). No other projects using the CPU, no restrictions in the BOINC client for CPU or RAM usage. The client has plenty of work, but no matter what I try it will not run more than 6 tasks/cores simultaneously. I can get it to run less than 6 by limiting the CPU usage to something less than 20% (just done for testing), but even at 100% CPU allowance it just won't do more than 6 at a time. If I let the BOINC client download work for other projects, it will happily make use of the remaining available cores on the CPU while the 6 MLC@Home tasks are still running.

Is this an intentional limit of the project to only run 6 tasks at a time, or am I missing something? I haven't seen anything like this before except on projects that give the option to specifically limit the number of tasks that can be run. I don't see a setting like that available for this project.

I have not set anything that would cause this. And I regularly run 10 concurrently on my Ryzen 3600, no problem. So I don't believe its a problem on my end. I can't think of what would be causing it.

I just restarted the system (again) and MLC is using all available cores now. No idea why it wasn't working right before..