stick with the nvidia gtx range 700 series or the 900 series are prety good depending on games & purpose really & power supply as u upgrading u going to need to up ur psu to suit to
the quad core version tho i would advise that ur cpu u have is prety good of the bat the core 2 duos are prety good cpus b4 intel changed to i series generation i advise find a beefy video card & a bit better ram & it go as good as any new gen around
stick with the nvidia gtx range 700 series or the 900 series are prety good depending on games & purpose really & power supply as u upgrading u going to need to up ur psu to suit to
there an online psu calculator u can use all i do is pick the card i wana use the cpu motherboard & set up add it to the calculator & it will tell u how bigger psu u need
yeah u can pick ur cards to suit ur situation & adaptors using a hmdi to dvi adaptor on 1 set up currently using 2 antec vp600 psus no issue overpowered but back up for more hardware later on