Asking for someone but their PC seems to only use half of the ram? we thought initially it was the ram sticks that went bad but I got them to upgrade from 8gb to 16gb. Previously it would only use 4gb but now it's 8gb, it's two sticks of ram and I'm suspecting it's the motherboard that's the problem? I want to make sure before deciding whether or not to tell them to replace their motherboard.