Im using Gigabyte GA-MA70X-UD3P amd mainboard with KHX8500D2K2/4G memory set ( code is 99U5316-066.A00LF). I wanted to add used memory and bough from internet 1 set KHX8500D2K2/4G 99U5316-043.A00LF. but these memories are not working as alone. I tried all combination. And also from bios tried to change clock speed to 800 and also to make them auto. But still giving beeps and not working at all. Is there someone who can help me about this problem. Do you think they have to work with the board or not supported?