You don't say which revision of motherboard you have, but here is the link for revision 2.1 (2.0 & 1.0 are also listed on this page): http://www.gigabyte.us/products/pro... .
The specs will tell you the slots available for video cards, e.g., PCI Express version 2.0. That will also tell you which DDR types your motherboard will accept. Also note the following note they have on their spec sheet: "please refer "Memory Support List" for detail memory support information.".
As for more information about DDR types, the higher the number the faster the RAM module is, the greater your bandwidth is. But a quick look over the spec sheet tells me you may be limited in your available options.
Let me know how you fare.