Aurora-R4, GPU upgrade from GeForce GTX 560 Ti?

I have an Alienware Aurora R4 fitted with a Nvidia GeForce GTX 560 Ti, and Windows 7 home premium, purchased from Dell in 2012. I play a game called World of Tanks which has upgraded to HD graphics which the card seems to coped with up to now.

Playing the game the screen went black and there was a loud buzzing sound. The PC rebooted itself, but the BOIS intro screen is corrupted with lots of exclamation marks and it now does back slashes on the "press cntl i to enter configuration utility" line. The screen now has small blue dots all over. On device manager there is a triangle with a ! mark, and Windows returns a Code 43.

I have uninstalled the graphics driver and all nvidia utilities. The VGA driver works fine with the lower resolution and all other functions appear to work correctly. Window has automatically reinstalled drivers including older versions which were stored on the PC, I have also downloaded drivers, all to no avail. The Code 43 remains.

I clean the inner area of the desktop to ensure it is dust free. Today I gave it a thorough clean, removed the graphics card, cleaned it and reinstalled it. All to no avail.

I have come to the conclusion the 580 is out of date, malfunctioned and needs replacing. 

I believe the options are limited because of the Motherboard. Is that correct? With that in mind, what is the best option?

Can you recommend a suitable replacement card the Aurora power unit can cope with and will manage the HD graphic demand a lot of games use. 

Thanks.

David