Can you still RMA your RAM, and did you get it as a kit? If so, I'd RMA the whole kit (both sticks), so you are guaranteed to get a new matching kit. If you replace only one stick, you're not 100% sure it'll run in dual channel with your remaining stick (although likely it will, just not guaranteed)
Originally Posted by J o h n R o g e r s
I thought that modern motherboards need to work as a pair? Or is that me that's misunderstood things, lol.
And no, modern boards not need a pair to function. However, a pair makes it function faster usually, because it enables the 'dual channel' functionality. It will run fine on a single stick, but better on two matching sticks