CPUs you can use with a 850W PSU

Assuming you already have a ~300W GPU, here's a compiled list of possible CPUs you can use:

CPU	TDP	Quick Buy
Intel Xeon 6737P	270W
Intel Xeon 6738P	270W
Intel Xeon 6740P	270W
Intel Xeon 6736P	205W
AMD Ryzen 7 9800X3D	120W
AMD Ryzen 7 5700X	65W

What CPUs can you use with a 850W power supply?

First of all we have to make an assumption regarding the rest of your PC, let's start by assuming you have a ~300W GPU. Also, we can assume that the rest of your PC components (MB, RAM, Fans, Storage, etc...) consume an additional 100W, and we'll have an additional 100W of margin. That leaves us with 265W for the CPU.

With 265W you can squeeze in CPUs such as Intel Xeon 6737P, Intel Xeon 6738P, Intel Xeon 6740P, Intel Xeon 6736P, AMD Ryzen 7 9800X3D.