hii, currently i have the following configuration
cpu:intel core 2 quad Q9300
gpu:nvidia 9500gt(512mb ddr3 ram)
psu:not a good one (planning to buy that also)
ram:2gb DDR2 (800mhz)
monitor:samsung(1680 * 1050 resolution)(planning to buy a full hd one in near future)
so i want to know if i upgrade my gpu to (radeon hd 7850 1gb), will my cpu bottleneck my gpu.
For a system like your I start with the Corsair TX-650 V2. It's a great all around PSU and on sale now at Newegg. If that's too expensive, then I'd drop you to the entry level Corsair unit, the CX-500.
First thing to do is get 4gb or RAM and make sure u are running Vista or wind 7 otherwise no point getting a DX11 card.
Second buy a decent maked PSU, anything 550w above will be fine (7850 is an efficient card) however if you plan to overclock your quad core play it safe and go for at least 600w. If you case has options for more fans get one especially if you are over clocking it.