It also depends on what is your resolution a gtx 980 is terribly overkill if you are under 1440p (and as you are coming from a gt 610 im guessing you are under that)
I use a gtx 970 and i never saw my gpu using over 2gb (playing in 1440x900) but im not playing gta 5 just mgsv and max pain both of thoes use near 1.2-1.4gb the only game i saw used 2gb was starcraft 2 (how ironic xD ) if you aim gta than my friend plays it easily maxed with a r9 280x in 1600x900 res if you aim nvidia than gtx 960 is your best bet but in your case in this budget range i would go for a r9 300 series card from amd it will give you most bang for your buck
(And im saying this while using a gtx 970 lol
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