Ur welcome. Have you ran any games? Curious about in game performance and temps in gpu-z afterwards. Other than temp related auto downclocking, can't think of anything. Maybe it's a dud that works half ass?
If you end up RMA'ing, call them instead of doing online. Stocking staus may hinder timely exchange if they make you stick with Diamond. I'd tell them you want whatever's in stock at time they receive it back, XFX, Asus, Sapphire, would be my top picks.