Precision 7540 - Memory that is PC4-2666 / BIOS runs it at 3200 and then is unstable

The laptop originally came with 2 Dell 8gb sticks running at 2666mhz.  When upgrading with Mushkin memory (actually 2 of these 2x32 kits https://www.poweredbymushkin.com/Home/index.php/catalog/memory/essentials/item/228-ddr4/1434-mes4s266kf32gx2) to give the machine the full 128GB of ram, the bios recognizes the ram as 3200GHZ and then the machine freezes fairly often and MemTest reports many errors before freezing itself.  The machine will only run at 3200ghz with all Mushkin sticks installed.

Currently I can only get the RAM to run at 2666MHZ if I use the original Dell RAM with one of my kits and then all works fine, but then only running 80GB and not using all that I bought.  So if the processor does not support 3200MHZ (processor is i7-9850H) then why does the BIOS keep running 2600MHZ RAM at 3200MHZ when the configuration will not support 3200MHZ?

Is there any way to force it to run 2666MHZ?  Really, isn't this a bug?