i used to have a gtx 960 and i recently got a rx 580 and when i used it i had around the same if not worse fps with the card but when i look at benchmarks people on games such as fortnite would get 200+ and i barely get 100 i have deleted old drivers and reinstalled some unplugged my gpu and put it back in overclocked it and nothing has workded please help
As a random guess I will go with CPU bottleneck.
It's hard to give any constructive advice without more details of the system you are running.
indeed some more info would be wise mobo type, ram modules installed, cpu type and number of cores, and what type of monitor you use eq with freesync or without and max hz.
btw when you have a 60 hz or 144hz monitor you should know everything above the monitors fps capebilities are discarded ever second or so, so 100 fps on lets say a 60 hz(eq 60 fps) monitor is discarding an average of 40 frames every second,then you are bottlenecking between monitor fps rates and gpu pre rendered frames.
The RX 580 is substantially more powerful but it depends on the situation for rendering with vsync etc.