over heating mac book 2019 intel i9 how to fix this

16-in 2019 intel MacBook Pro heat and performance:

This computer was built with a ninth generation 14nm Intel processor. The only way to meet the target performance was to make it a six or eight core processor. This processor generates an enormous burst of heat when it does Turbo Boost, and there is only one cooling rail shared by both the CPU and GPU. So getting Either side too hot ramps up the fans.

This processor was supposed to be an eleventh-generation 7nm processor, but intel is three years late, and is only starting to ship its tenth generation 10nm processors now.

The drive in this computer is more than 100 times the typical speed of computers a decade older. If you have installed software that wastes computer resources on a regular basis, but used to be drive-speed limited, such as speeder-uppers, Cleaners, Optimizers, Virus Scanners, third-party file Sync-ers such as DropBox, OneDrive, or GoogleDrive, or a VPN, it will do busywork at previously-impossible speeds — heating up at a ferocious rate.

Apple DID redesign the cooling system for this specific Mac. New, high-efficiency fans are used. But for some uses, that is still not enough.

Some of the best advice is to install Turbo Boost Switcher and turn off CPU Turbo Boost. This reduces the huge sudden overheating brought on by Turbo Boost, that simply does not translate into real-world performance gains.

For external displays, changing away from HDMI to DisplayPort family (or to DisplayPort over ThunderBolt or USB-C) will reduce the Voltages and slightly reduce the heat generated. It is a good thing to do, but it may not be enough to solve this issue by itself.

If it is indeed the external card, consider additional cooling for the card. I'm not sure what's available; a buddy of mine has a small fan blowing on his. Kind of clunky looking but he says it works.

Also be sure you're not impeding air flow into the Mac or over the exterior surfaces in any way.