I can highly recommend the 1050 Ti. Not the standard 1050 it needs to be the Ti model. It needs no external power, runs pretty cool and has about the same power as a 770 in most titles.
I have an aged 770 and I just advised my friend to get the 1050 Ti for his similar rig to yours and it is really a lovely performer at 1080P
While most dont require additional power, get one with a 6 or 8 pin. I've spanked mine upto 146% base gpu clock andfor that you need more power than pci can deliver. It runs cool still. (Msi gtx 1050ti gamimg x is what i run)