i bought this system in 2009. 3.2ghz intel dual core, asus p5q turbo, 4 gb ddr2 ram, a gtx 260 (512mb) i want to upgrade to a gtx570. can i do so without having to replace any other parts? if i have to what are my best options
i never saw GTX260 with 512mb memory. normally it has 896mb of memory because of it's weird bus configuration (448bit). btw GTX570 should be a good step from your GTX260 but your processor definitely going to bottleneck the card. also you might want to check back your PSU since nvidia recommend 550w PSU for GTX570 (500w for GTX260)
I suggest at least a gtx 560ti or gtx 570 minimum to be a worth while upgrade. I got a gtx 460 and soon two gtx 280. I already got one of my gtx 280s and it is on par with a 460. A gtx 560ti will be a decent upgrade but fermi based cards are not built to well.
Just go ahead with a new psu along with the new card. A core2 duo can handle a 570 but it is borderline between just being enough and being a bottleneck. Floating point wise a core2 duo is ok but 775 never had good i/o performance so that will hold you back. I suggest going ahead with the psu upgrade and the new card with a rebuild later on down the road. As for the i7 920 it is a good cpu but a hot one and very costly platform thanks to the board.