Now, I wonder which graphic card best fits configuration. I need it just to be compatible with the other elements. I mean, you see, this is not a gaming machine, I don't want a hi-end graphic card. Because, if I buy a hi-end then the processor will be the bottle neck. Even I don't have money for this. And also I want a card which will not be the bottle neck of the system. The processor is 3.4 and my rams are 1600MHz. so I hope it will be a relatively fluent machine. Which card will best work in and not make this configuration stuck? Or won't be, let say, "better" than the system.
My options are:
GTX550 (I have a really good priced one I hope you'll say enough)
GTX560 (not the best price but if you say so I can push my budget)
GTX570 and HD6970 (I hope you'll say these are hi-end and I don't need them)
You may actually look onto a 7850 these days. They're like <$200 these days. Yes, go for AMD, no problem, even you prefer nvidia cards. But if those cards are your only choice then I would go with the 560.
Well Sorry for being not specific on the bottleneck thingy. What I actually is trying to say is that your processor is pretty much good for any single-configuration of graphics card that are currently in the market (yes, the 680 and the 7970 GHz included).
As for the Power supply, Are you getting that, or you already had that? If you already had that, I will recommend to not go for a card that consumes power above the 7850. Meaning no 560, only 550 Ti . But if you want to get it, I don't recommend getting it because I don't think it's a great Idea to get a cheaper power supply. A Better one will give you more benefits than what you will pay more . One of them: