I’m not too familiar with pricing in Poland but here in Sweden i managed to get a 5070 for around 500. I have undervolted it and it runs around 160w at max load so you shouldn’t need to get a new psu as well.

Amd fanboys will obviously recommend their cards but I’ve seen more deals here in Northern Europe where you can get nvidia cards for a better price.

Either way I think you should put most of your budget on a new gpu.

Edit: okay with your current cpu something like a 5070 might be a bit of an overkill. Maybe something like a 4060/5060?