Yes, the graphics card memory type is independent of the system's memory, so you are not limited by that. What you have to look at is the graphics port on your mobo (PCI Express x16 in your case) and your PSU.
If you can provide the wattage on your psu as well as the card you are interested in, along with the specifics on the rest of your computer (i.e. cpu, ram, hdds, etc.) I can let you know whether it will work or not.
Alternatively, you can use this
link to calculate your projected consumption and compare it to your psu's wattage.