So I just got my R7 and wanted to upgrade my memory. It came with only 1 stick of 8gb ram 2666 in slot 1. I want to upgrade simply to 16gb 2666 for now I might expand it later on. But I'm wondering if I get an extra 8gb ram stick with the same specs and CL should I put it in slot 2? Or would I need to put it in slot 3 or 4 if they were different manufacturers?