Upgrading graphics card

[Evilmatic]

I have a hp pavilion elite hpe-112y and looking to upgrade my graphics card. Right now I have a 5570 Radeon HD, but I want something better. What's the best possible graphics card I can get without having to upgrade my PSU? Thanks in advance.

 

[thespaceduck]

I would say a gtx 750 Ti. It has remarkably low power consumption.
Check this out: http://www.tomshardware.com/reviews/geforce-gtx-750-ti-review,3750-21.html

Kudos,
Albert