I had a 4670k in an old system. What are you aiming for? There are games that will be unplayable regardless of gpu choice, for example I remember trying to run Gears 5 and it was unplayable because of the cpu, BF1 was playable but not enjoyable and upgrading the gpu would not have helped for these games. Point is a gpu upgrade may not achieve what you want, what games are you wanting to play and what is the aim, same fps but better game settings or higher fps and better game settings?
Uhh I'm currently just playing lost ark, but it is weird cause the cpu utilization is low around 50-60 sometimes 70 ish but the gpu usage is always at 90-100% having 30fps with 1600x900 windowed mode, lowest everything, I have tried other games such as Genshin and the fps was 60 at 1080p, sometimes dripping down to 58 so Idk if it is just the game or what so I concluded that the gpu was bottlenecking
It also just recently happened to me too( the absurdly low fps), but yeah I can't have constant 60fps with it and recently the fps is just so low idk what was going on
I tried, DDU and reinstalled newer gpu drivers but the problem persists.
I recently just re-installed a fresh windows 10 copy for about 5 months ago too so I haven't considered doing that.
I also couldn't run Spiderman Miles morales / Amazing spiderman remastered @ 1080p 45-60fps lowest settings if we are talking about AAA titles. (i have tried it, runs like 20-30fps @ 1080p lowest which is unplayable for me at least). I also tried playing Elden ring to try to get at least 60fps @ 1080p with lowest settings but somehow it only runs at 20-30fps 45 at max.
Upgrading the Gpu is my last resort as of now (or so I think, and I could stand corrected).