enter all your components here :
https://www.newegg.com/tools/power-supply-calculator/
there are many wattage calculators like that .
it gives you all the wattage you need , based on your all pc components.
in call of duty series , they are mutually exclusive if you play for yourself
they even have an fps counter at the top for you.
maybe they are indepently exculsive in other games i don't play anymore.
if it's capped ,then it's capped either within the game settings
or like you menti0oned your self , it's capped within your nvidia / amd / intel driver software since you're experiencing it in every game you play online .
2.4 ghz band is almost phased out like 3G .
even 5 ghz is considered old is being replaced by 6 ghz .
even your microwave , could interrupt the 2.4 ghz band .
hope that helps.
maybe you always play with the kids around you in USA and you don't notice ?
like i told you in mw2 it matters how good your latency is , it Does affect your FPS compleely sir.