suggest me a best Gpu upgrade for my current Gpu (MSI N580 Twin Frozer II)

[bullooka]

My specs are:
Cpu: Intel i7 2600k
Mainboard:Asus P8 p67pro
Gpu:MSI N580 Twin Frozer II
others are 8gigs of ram and 2 tb hdd,

I did'nt specified my current psu because i want you to suggest the psu too.
So, please suggest me what is the best Gpu upgrade for my current system.
(If possible suggest me two Gpu:1. Best one for my system, 2. At lowest budget.)

And i mainly use my pc for Gaming.

 

[Narzter]

bullooka, it really depends on your price range and what kind of "gaming" you're into.

 

[MT6Anime]

If you give us a budget would could give you something as Narzter said but if could afford it I would go with a GTX 970 it has an outstanding price/power ratio. A 550W PSU should do for a 970 I think.