CPU cores maxing out...

About 2 weeks ago, my 12-core Mac Pro cores started maxing out. It is happening about once an hour or so, to the point where I'm getting the spinning wheel and all 4 of my big displays are flickering. The problem lasts for a couple of minutes, then everything is back to normal.

From terminal, a top command only shows "kernel task" at 1600-1800% at the top of the list.

I have tried reading the console logs, but to be honest, I don't know what I'm looking at.

I have tried shutting down running apps one at a time to see if the CPU core usage drops, and none of the apps (or lack of) seem to affect the problem.

I have run Little Snitch to see if there is a network component associated with the issue, and I can see no correlation there either.

Any ideas on how to proceed further to nail this down?