I have i5 9400f,rx470 4gb asus strix and 8gb ram ddr 4 2400mhz and in fortnite and warzone is so laggy
In warzone frame drop and latency increaseAre you talking about internet lag or frame rate drop/stuttering?
The RX470 is also fairly low end by todays standard being substantially less powerful then even a GTX1650 Super.
Frame rate is a hardware issue and probably has to do with your RX470. As I said that card is fairly weak by todays standards. If you updated the AMD drivers recently maybe roll back a version or two and see if older drivers are better.In warzone frame drop and latency increase
2x4gbIs your RAM 1x8gb or 2x4gb? Either way 8gb is a bit low and some games will stutter.