any ideas why CPU usage would never go over 25%?

hi, we have a powerful windows server with 200GB RAM and 40 cores. i've been using it for a few weeks now, and mserver.exe never seems to use more than 10 of the cores. mserver does say "using 40 threads" so they're all available is it just rare for any SQL query to use more than 10 cores at once, or is it possible i've misconfigured something? thanks