yagtastik :
Budget would probably be like $700-$800 give or take.
open your case and look at the power supply
post back make and model
you might need to also upgrade this
if it is a half-way decent unit with the proper pcie cables then either a rx 580 or a gtx 1060 6gb are what you want
newegg, amazon, tiger direct, NCIX, B&H, are all good