CPUs you can use with a 450W PSU

Assuming you already have a ~100W GPU, here's a compiled list of possible CPUs you can use:

CPU TDP Quick Buy
AMD Ryzen 7 5800X3D 105W
AMD Ryzen 5 7600X 105W
AMD Ryzen 7 7700X 105W
AMD Ryzen 5 7500F 65W
AMD Ryzen 5 5500 65W
AMD Ryzen 5 5600 65W
AMD Ryzen 7 5700X 65W
Intel Core i5-12400F 65W
AMD Ryzen 5 5600G 65W
Intel Core i3-12100 60W

What CPUs can you use with a 450W 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 ~100W 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 105W for the CPU.

With 105W you can squeeze in CPUs such as AMD Ryzen 7 5800X3D, AMD Ryzen 5 7600X, AMD Ryzen 7 7700X, AMD Ryzen 5 7500F, AMD Ryzen 5 5500.