Its supposed to be blocked electrically it wont work. This post is more about the "Lucid Chip" and less about the motherboards features. So let me fill you in 4 of them run at 16X Yes 4, not 2 like yours. Like i said all the features aren't listed here so maybe you didn't know that. Anyway motherboard makers know about the spacing this when looking at a board u know what slots will be blocked. Its as optimized as it going to get so i dont know what u mean about that. People continue to say that about every board but dont stop to think.
If your only going to crossfire ud still have 2 16X PCIE free + PCI for a sound card or anything else. Thats if u use the first 2... And since 4 of them run at 16X you woudlnt have to use the first 2 to crossfire. You could use the next 2 down. The switches AT THE TOP of the board next to the buttons turn them on and off. Since u can do this to 4, scaling wouldn't go down. And the on-board sound this one is the full Supreme FX (no bs). Theres no reason to add a card.
You wouldn't buy this kind of motherboard to be server or full media center ect. "using all the ports" They have motherboards for that, ppl who trifire/quadfire have one thing on there mind. People who buy boards like this OC for fun or game. Its a monster board.