Dell Precision 5530 - Thermal events

My 5530 has 64GB ram, nvme drive, SSD drive,etc.  So maxed out.

Working fine until recently when it started experiencing thermal events (crashes).

Things I have done to try and solve the issue.

1.  Updated BIOS.

2.  Fans have been replaced.  Do not growl and run correctly.

3.  Opened up the computer and cleaned it out removing the dust.

4.  Removed Heat sink.  Removed all the old, hardened thermal compound.  applied new Artic MX-6 

     thermal compound and reassembled the computer.

5.  The computer is sitting on an aluminum stand so it is NOT sitting flat on the desk.   There is nothing 

     obstructing the vents.

6.  Disabled the Turbo feature in the BIOS.

Still having random thermal events (System board thermal trip).

Anyone have any other additional ideas on how to solve this?

Thanks.