I'm a bit upgrading my PC, and now I'm choosing GPU for me (my rig: phenom ii x4 945, 2x1gb ddr2-800, antec 550w psu). As i won't uprade my RAM or go to new mobo with ddr3, I don't which graph. card and screen (1920* or 16xx*) to choose, because of bottlenecks.
Can anybody help me which screen and GPU to choose (max price for gpu is hd7850 level) and are there any bottlenecks from RAM to GPU?
2gb is not enough. Go to 4gb first. Lack of ram causes all sorts of performance problems.
Yes, it is not as cheap as DDR3, but a 2 x 1gb kit is $30, or even a complete replacement 2 x 2gb is <$50.
As to which card, you will get fair value for your dollar at every price point except the very top.
Buy the strongest card you feel willing to pay for. Your X4 will be fine.
7850 is very good, and you may find the equivalent GTX570 at a better price.