Upgrading my old rig

[Necroire]

Current specs:
ASRock B75M-DGS
i5 3330 Processor
PowerColor HD7770 PCS+ GHz Edition 1GB
8GB RAM
SeaSonic S12II 520 Bronze 520W

Looking to upgrade my current rig to run smoothly on my DELL U2312HM (1920x1080)
As my current rig is giving me bad fps and constant fps spike during gaming. Recommend me a new graphic card that would allow me to run smoothly on my current monitor. Budget: $300

PS: Is there a need for me to upgrade my current processor? Wouldn't mind spending if there is a need.

Thanks.

 

[Jian19]

Gigabyte 270x ~ $299

Might wan to list ur case out so we see can fit anot..

 

[Necroire]

Gigabyte 270x ~ $299

Might wan to list ur case out so we see can fit anot..

using Xigmatek Asgard XP case.

 

[Jian19]

Should be fine ~

 

[Necroire]

Should be fine ~

might want to cut my budget to $250, what could be the best card to support my u2312hm @ $250..

 

[Jian19]

PC 7870 ~ $259 @ tradepac