you won't have a problem at all. actually, ddr3 does not support gddr5 (what's on your graphics card). but fortunately, all graphics cards come with their own set of ram built in, so you don't have to worry about that at all
the ram of the motherboard and GPU are not dependent on each other, they have no relation in terms of compatibility.
just think about it, what we have so far for motherboards are just DDR3 (and older), we dont have ddr5. If they are related (gpu ram and mobo ram), then we should not be using gpu's with (g)ddr5 right?
but we are, because they are not dependent on each other. so you are fine. the only compatibility issues you may encounter is, if you have an older slot which is AGP, and if your card is PCI-E