I'm not personally a high-framerate kinda guy, so I'm a little out of my element in that regard.
What are you using as a GPU now?
A simple thing to do to test your CPU's capabilities is to turn the resolution and details down to the minimum. Do the games run at 144fps or more, or is the CPU maxed out below that? If the CPU is maxed out, then no GPU is going to help it get you to 144fps.
If the CPU can handle it, then you're looking for a GPU that can do 1080p @ 144fps consistently. That's where you'll have to poke around and see what GPUs are needed to get that kind of framerate at 1080p with the details you want.
EDIT:
@hotaru.hino brings up an excellent point. Some older motherboards, particularly OEM boards from Dell, HP, and so on, are notoriously finicky about working with newer cards. If the motherboard doesn't support UEFI, it may not work with cards in the last generation or three.