What exactly did you upgrade?
If it happens to be a different motherboard, did you do a clean install of Windows? That's necessary.
I recently upgraded my computer, but I've been having some major issues. Everything is running very slowly; all the games I've been trying to play have severely limited frame rates, even when my computer parts beforehand had great FPS. I'm not exactly certain what is going on. Whenever I move my mouse, furthermore, any game's frame rate significantly tanks and is awful, though I believe that my graphics card is the cause of the issue, though I can't say for certain.
I've tried clean booting, removing and reinstalling drivers, decreasing polling rates on my mouse (which helps a little bit), installing drivers for my monitors, system file checkers, and so on and so forth.
Here's my part list.
16 GB DDR4 RAM 3000MHz
ASUSM z370-A LGA 1151
GIGABYTE GV-R939G1 GAMING-8GD