The best one that should work is the EVGA GTX750 which is $120 at pcpartpicker.
http://pcpartpicker.com/part/evga-video-card-01gp42751kr
It's the most power efficient and the value can't be beat:
http://www.anandtech.com/show/7764/the-nvidia-geforce-gtx-750-ti-and-gtx-750-review-maxwell/13
*Look how much faster the GTX750 is than the HD7750! (56 vs 33).
POWER:
My calculations and looking at Amperage recommendations indicate there should be no problems. For example, your PSU can provide 228W on the 12V rail alone., but the Total for a typical system under load is 178W.
The GTX750Ti recommended 20Amps, and yours has 19Amps so again, not seeing any issues. There's no 6-pin connector for the card I chose either (uses motherboard only).