Want to buy new graphics card

So I think my Radeon HD 6800 series graphics card is failing on my Dell XPS Desktop that I purchased in late 2011.

I kept getting blue screens of death when playing a couple of games, ArcheAge and Kingdoms of Alamur.

My thread for this is located at:

BSOD Playing Archeage and Kingdoms of Amalur

I have my doubts that it is the driver as it was crashing with the latest AMD Catalyst Control Center and drivers before I reformatted my computer.

So I think I may need a new graphics card. I just don't know where to start and have a few questions.

My concerns are:

1) Knowing that my graphics card is failing and not something else.

2) Getting a graphics card that is better than mine.

3) Making sure I have the right PCI slots.

4) Making sure my power supply can handle the new card.

Any help or advice would be appreciated.

Thanks,

Ryan