All we have so far is 3 slot wide, OR.. a 'little wider than two slots. I use a 5 slot MB, classify myself as a 'creator'. justifying 3090 expense, use two cards presently and two slots have solid state hard drives.... one O/S, one backup and data quick access. So without knowing 'Thickness' would be worried about even buying even a single 3090 card and having slots available. I really don't want to convert a entire computer system cooling system to 'narrow a card', to enable what the 3090 is really sold for, tying together two 3090s memory. Looking forward to what comes out in info from the product providers on this issue.