Sandwich refers to the layout of the case. Dan A1, Formd T1 and Ghost S1 are all sandwich layouts. Which means you have the GPU on one side and the mobo, cpu etc on the other.
I'm pretty sure Optimum Tech tested the ref design in an SFF case (the T1 I believe).
I would avoid reference in a sandwich layout, personally.
Edit: oh, 3070. Does that cooler blow through like the 3080s and 3090s?
Cold War has allocated all available VRAM on every system/GPU I've ran it on. 11 on 1080Ti, 10 on 3080 (with 4K pack), 6GB on 1060 and 8GB on 580. Every single time. 3440x1440, 1080p. Even 720p IIRC.