lets try explaining it another way.

Lets say one of your servers is talking to the DSS and no others. The very most throughput you will get is 1 gigabit. Lets say a second server starts talking as well, now you have 2 nics talking, but each only gives you a max of 1 gigabit. A 3rd server starts talking and now you have 3 gig of data flowing, but the most anyone of them will give you is 1 gigabit. Think of a 2 lane highway as opposed to a 6 lane highway. All the cars go the same speed (55mp or 1 gigabit), but more of them can get from point A to B simultaneously as opposed to the 2 lane highway (where cars still only go 55mph or 1 gig) but less of them can get from point A to B at the same time.