@Ian_Barnard is spot on about laptops.
Recently I’ve been swapping some AMD desktop CPUs to cross the threshold. Removing AMD Athlons for Ryzen 3s.
AMD’s AM4 desktop socket takes an impressively wide range of chip, so current desktops with uncompatible chips can be fixed…for the price of a new CPU.
Intel went through a raft of desktop changes around the cross-over time. 7th Gens were Kaby Lake, 8th Gen were Coffee Lake and they’re not interchangable.