i am going to buy a new gpu so suggest which one of them is good gpu
1. xfx 7790 1gb ddr5
or
2. sapphire amd ati r7 260x 2gb ddr5 oc with boost
The R7 260X will be better in terms of newer drivers and VRAM(If your into high end games and big resolutions).
But the 7790 beats the R7 260X in some cases. Better go for the Sapphire ATI R7 260X 2gb DDR5 OC with boost.
The CPU choice depends on your budget and on the type of games you're going to play. Assuming Intel as the better CPU choice is wrong, where multiple threads matter, AMD could leverage its multi-core APUs and technologies such as Mantle to have its products perform on par with Intel CPUs. My only advice then is to look at reviews, such as this one: http://www.techradar.com/reviews/pc-mac/pc-components/processors/amd-fx-6300-1117533/review and then make your mind up according to the product with the best priceerformance ratio.
Eh. Seems like OP is set for the Intel piece. Caldwell's suggestion is good, go get it. As for PSUs, anything with at least 500 watts and an 80+ certification would work for you.