Upgrade GPU or start fresh?

Thanks for any advice!

I built my PC back in 2012. I'm starting to get some issues gaming, but it's held up admirably well.

Intel Core i5-3570K 3.4 GHz Quad-Core Processor
ASRock Z77 Extreme4 ATX LGA1155 Motherboard
Asus Radeon HD 7850 2 GB Video Card
SeaSonic M12II 620 W
4x G.Skill Ripjaws 4 GB

It appears I could just buy a new GPU and it should work since my power supply is 620W and my Mobo has a PCIE x16 slot. It also supports up to 32GB RAM so I could double my memory.

But is that even worth doing? Or should I get a new Mobo and CPU and just start fresh?