Recently I moved the Haswell system home and brought the Clarkdale to the office. If you recall, the Haswell system has the Silverstone SFX ST45SF-G while the Clarkdale has a traditional ATX Cooler Master 500W. Both systems have front intake fans. CPU are both passively cooled. Only the Clarkdale system has a video card, and it is a PowerColor HD5750 with an open air cooler.
When I specifically listen for it, the noise from two computers were equally noticeable. The Clarkdale system is probably louder, but I find it less annoying. The noise blends into the environment very well as I would easily forget that the computer is there and running. The Haswell system, on the other hand, generates a higher-pitched sound that is obtrusive and unpleasant. The higher frequency may be a combined result of smaller case (TU100 vs. Q11), smaller intake fan (120mm vs. 140mm) and smaller PSU fan.
The point is that not only the intensity affects user experience but other characteristics of noise play a role as well.