I'm curious - why exactly does a shroud work so well? The main reason i can think of is that it minimizes the dead spot of the fan, which is admittedly pretty big for a 120mm.
Does it also reduce noise? Are there any other reasons it helps? How much % temperature difference can one reasonably expect with a shroud?
Also, is a situation where a shroudless setup would work better than one with a shroud possible?
In addition, what is the point of diminishing returns with a shroud - how far away or how near can it keep the fan before it starts becoming a problem?
Thanks