Some games are graphics limited like fast action shooters.
Others are cpu core speed limited like strategy, sims, and mmo.
Multiplayer tends to like many threads.
You need to find out which.
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To help clarify your CPU/GPU options, run this test:
Run YOUR games, but lower your resolution and eye candy.
If your FPS increases, it indicates that your cpu is strong enough to drive a better graphics configuration.
If your FPS stays the same, you are likely more cpu limited.
CSGO seems to be one of the more cpu dependent games.
Your psu is of questionable quality and may not be able to deliver the advertised 500w.
Tier 6, I think on this list:
Credit to @Starelementpokeand @Energycore for helping out with this long-awaited refresh of the old PSU tier list by Aniallation (who previously went several months without logging in), leaving the old list in need of help. This is simply an update of the list that was flawed in creation by the P...
linustechtips.com
That will limit your choice of graphics card upgrades.
Here is a handy chart of psu requirements for graphics cards:
Credit to @Starelementpokeand @Energycore for helping out with this long-awaited refresh of the old PSU tier list by Aniallation (who previously went several months without logging in), leaving the old list in need of help. This is simply an update of the list that was flawed in creation by the P...
linustechtips.com
The RX cards are cheap, but power hungry.
You might be cautious and buy a card that needs no more than 75w.
Here is a list with performance rankings:
https://www.tomshardware.com/reviews/gpu-hierarchy,4388.html
For reference, your vega11 is about the same capability as the GT1030 on the list.