230V UK mains voltage here, that improves efficiency, which will reduce heat output and thus noise.
At 599W DC output, the ZM1000-HP recorded 87% efficiency, thus 89W of waste heat. Not a lot for a 140mm fan and a heatpipe cooler to dissipate.
I can't categorically state that the ZM850 I have is 14dB at full load, but what I can say is the subjective noise pressing my ear against the side, along with the amount of airflow coming out, is exactly the same at full load as it is at idle. It's arguable the unit could be producing a bit more noise at load and me not notice, but frankly, that's a little irrelevant. When testing the unit at around 550W load with a very quiet card [an Accelero-cooled 4GB HD5970, albeit a faulty one], the PSU was still clearly spinning at idle fan speed. At 700W i think you'd struggle to get any components that would allow the PSU to be audible.
I'm not going out there saying the PSU everyone should buy is the Zalman. As good as mine has been, they are older units, and there are more efficient models, including like the AX, ones with fans that turn off completely at low load, which will be superior for silent idle systems. However, what I was trying to illustrate was that 'noisy' PSUs can become quiet PSUs in a case with a good cooling layout, and PSUs that would otherwise be written off are very viable with the right case.
Indeed I think that (now) I understand your point.
Just for the sake of talking about, I've only said that without hands-on experience it's not easy to me evaluating such a situation.
For example, I have a modest Wolfdale based system cooled by a Scythe Kabuto. We can't rely upon TDP as the CPU is mildly overclocked (3.33GHz vs 2.5GHz stock) and slightly undervolted (1.15V vs 1.22V stock), but to summarize I am able to cool (around 63°C with an about 22°C ambient) it when running 2 instances of Prime95 plus Furmark 1.8.2 with the fan at about 650-680rpm (even if the heatsink is also close to a 500rpm exhaust Slipstream).
So I can argue that a 600gr. six pipe heatsink with a total surface of 6042 cm2 may cool more than 65W (likely around 80W) with a modest 11-13dB output noise.
Therefore, theoretically it *could* be possible to cool 90W of waste heat (at 242V) with a slightly larger fan at a similar modest noise level (it would seem the Zalman kicks in when its temp rise excess the 14°C, while the Corsair fan ramps up when temp rise just above 7°C).
But does the single heatpipe/two blocks Zalman 60x80mm heatsink be comparable with a somewhat massive 120x130mm Scythe Kabuto?
And what about if and when the waste heat was more, as at 700W DC or 850W DC levels (or with lower voltages)?
Frankly, I don't know (and I have no more guessworks to make about).
Surely it will be very interesting if MikeC and his good friends would extend the open air tests to all the recommended PSUs to give us more information about real life conditions.
Thanks for sharing.