Honestly, you might want to save up for a whole new system. That processor is quite old (FM2+ socket from around 2011) and uses DDR3. Your current GPU may already be bottlenecked by that CPU.
My bad, I misunderstood. The RX 470 is likely the best GPU you can pair with that CPU. It should work fine for the games you currently play, just with better graphics.
Just a heads up, the RX 470 needs extra power. Make sure your power supply is at least 300W and check if it has a dedicated 6-pin PCIe power connector. Avoid using any Molex/SATA to PCIe adapters; those can be fire hazards.
Got it! I also noticed my motherboard says ‘DDR3’. Does that mean it only supports DDR3 video cards, or is that just for RAM? I had a video card before that broke, probably because of this.