Pci Slot Video Card Is A Pci Express X16 Video Card Compatible With My Pci Express Slot?

Is a pci express x16 video card compatible with my pci express slot? - pci slot video card

I intend to upgrade my graphics card to the computer from its original dies. So I found a line, but it is a PCI-Express x16 and has a memory interface DDR2/GDDR3. And my computer video card slot is a PCI-Express and the original DDR memory interface. So I want to know if I work on card or do not have to buy with my computer?