gpu gt 730

I'd like to upgrade my graphics, so I'd like to know what would be the best option Pegatron Corporation 2AB6 has a DDR3 slot and PCIE 2.0 x 16 I've seen people talking about using GTX 660 but I checked this one is DDR5, how could be this possible? I was considering to use a ZOTAC GT 730 4GB...