Help me to upgrade my PC

Hello guys! I’d like to ask for recommendations on the best CPU and GPU compatible with the H81M-K motherboard, and what PSU wattage I would need for that setup.

Also, what would be a good GPU to pair with an Intel i5 4th gen if I decide not to upgrade the CPU yet?

I’d really like to upgrade our old PC, but I don’t have the budget to buy a new one. I’m just a newbie. Thanks a lot for any advice!