I'm not sure what is the best or highest powered Graphics Card I can install on an older Gateway FX510X Desktop. I currently run a Pentium D (worst Intel made) dated 2006. However, the PC runs smooth. I did upgrade a new Graphics card 3 years ago, a NVidia 9600 GT. It does have a PCIx16 slot available. I hate to rid this PC, it really is a wonder for 10 years old, all original parts excluding Video Card and Memory. It is a 32 bit OS, with capabilities of 64 Bit, but do not think installing 64 bit OS is wise, all other drivers will not work. It has a partitioned drive, with Windows 7 Professional, and Windows 10 Pro on other side, both work flawless for its age and old CPU @.2.87 Ghz. Any thoughts? I woud like to stick with NVidia. Possibly a GTX. This is not AGP, but PCI. Thanks in advance