I have two options I have a budget of about 400 euros and I am thinking of upgrading as the PC is getting a little unresponsive in general use and gaming. Leaning towards option 1 as the cpu is almost always above 50% usage at idle as I use my PC as a server for jellyfin and some other services ,but with them off in-game the cpu is almost at 100% in tf2 and pretty much any other game and the gpu is at 70% unless in cs2 ,then if the quality is set any higher than low it is a literal slideshow.
Option 1:
MSI Pro b650-s wifi
AMD Ryzen 7600
Crucial/Kingston ddr5 2x8gb
Option 2:
Nvidia rtx 3060/3070 with broken HDMI output (both used)
Requirements:
Motherboard Atx
Cpu am5
Must be available in Lithuania/EU for used parts only skelbiu.lt or eneba.lt
Option 1 would be the better way to go first imo. The 9400 was an ok CPU but those 9th gens are really starting to show their age. You're also holding it back by only using a single stick of ram. Your RX580 can hold out a bit longer with a better CPU and faster memory in dual channel, but if you upgrade the GPU first you'll still be seeing the same performance issues. If you do go with option 1, make sure you have the proper mounting kit for your heatsink. AM5 is very different from 1151.