Thank you ser, I will check it out. By the way, all these graphic cards are ok with my motherboard? (I know it's another hard answer, but I really don't have the skill to know it)
Not hard to answer. Yes, they are all compatible with your motherboard. Just make sure you have a decent PSU to power a gaming card, and enough space in your case for a 10"+ dual-slot card.
I'd recommend an HD 7870 or GTX 660 - both can max out games on 1080p.