Please note that the two reported temperatures from the single-sc are not everything. This values are coming from two sensors, which are somewhere between a 8-ASIC cluster and the +1V regulation for this cluster. They are not in the ASICs or inside the 8-ASIC cluster circuit nor inside the +1V regulation circuit.
Even if you may see only a small temperature increase by changing the fans or even see a decrease by changing the whole setup by e.g. opening the box or something like this, it doesn't mean that the ASIC's or any other important parts are not getting much more hot than they should. Also watch the hardware error rate carefully!
Soon I'm ready to report my results from looking for fan alternatives....
In effect, what you are saying is...the chips are actually hotter than reported. Correct?
Is that a good thing?
Not necessarily. The DC/DC supply generates a significant amount of heat as well, and doesn't have the benefit of the nice heatpiped cooler attached to it. It's possible that the temperature reported from the sensors close to the output inductor could be higher than the die temperature.