Saw that the board came with 3 connectors with space for 6 more. Does that mean I could just solder some more sockets onto it and it'll be able to handle 9 hashboards?
Tupsu has had several boards connected to the early batch boards which came with the other receptacles and yes, they work. He also did this with the S5+ as it appears that was the first s7 boards.
Search his posts and you will probably find it fairly quick.
By the way, ignore the other reply which was oh so helpful. She wants to be a moderator so the little bitch pretends to be one. She is a very bad dog and it is best just to put little bitches on ignore unless you want to see how they reply to a newer miner. If so, unblock, read / reply as needed and plop back on ignore because there will not be anything worth reading after that one. She just gives you negative trust ratings that don't mean anything.
Good luck, and the answer is yes, you can solder more sockets and they will support more. I cannot commit to the total number, but Tupsu has posts which I believe answer that very question.
If a real moderator comes by and says something it is because the poser little bitch reported the post like she usually does. Don't ignore the real mod, but never pay attention to the lil bitches.