What card for my Birthday?

im going to be able to upgrade my little Radeon 6670 for my 18th birthday this october so i have some money to spend. all the videos ive seen have amazing reviews on the Gtx 780 with it almost matching the titan on alot of the bench marks.  It would be a massive help if you guys could point me in the right direction. i have around £550 to spend on a GPU and want to get the best i can for the money. 

Thanks

A birthday card :

 

http://static.someecards.com/someecards/usercards/MjAxMy1hNDEyZTk0MTAxNTAxZWM1.png

Gtx 780 is definetly your best option. However, what are your other specs? You may want to upgrade something else as well and opt for A 7970 ghz or 770. Honestly, your wasting the power of a 780 if your at 1080p.

If you're going from a 6670 then am I safe to assume that you psu is a low powered one yeah?

7970 or 7950 / 760 or 770 with a new psu for that money would be worth a look.

As tryphaa says what are your other specs? cpu, board, ram, psu etc.

 I would suggest going with a 770 because as noted above the 780 is a waste at 1080p.

Well this is from his profile.

computer specs: 

My computer has a AMD 8350, AsRock 970 Extreme3 motherboard, 16GB Corsair red 1866 Ram, Corsair 750W 80+ PSU, InWin dragon slayer case

thanks guys been a great help. ill look at getting a 770 then and getting that will be saving me some money for other bits as well