I'm not an OSX expert (and everyone on this forum knows that!!!) but because of its 'nix under the bonnet I take an interest in the OS internals. I've heard for a few years of the bug that allows the OS to run away with the CPU and overheat the system. "kernel_task" bug. So hopefully this issue that you are having is not directly related to the fact it's a 12-core box. You state that you've searched all four corners of the planet for a solution so you've probably read all about this already (but just in case):
How to Fix Your Mac's "kernel_task" High CPU Usage Bug
And this (mentioned in above link):
How to fix kernel_task CPU usage on El Capitan | Viktor's ramblings
Ultimately it means "putting your fingers under the bonnet" which could mean having to restore the system again if it goes wrong. However, you may decide that you have nothing to lose.