hello,
it seems that you have about the same goal / questions than i had about finding a near silent high end PSU :
viewtopic.php?f=6&t=68217
the best of all is the EVGA supernova 1600P2. fanless until 800Watts.
if you want lower price, well visit the link. I had very helpfull answer.
My build is not totally silent (3x AP181 @700 rpm is audible), but very good nonetheless.
The purolator guy just delivered the new snow silent PSU, will test it this week end
I wish you good luck for your 1080 rad build ! i like overkill !!
ah and for your question about the 180 fans :
I have a couple models, and i tested them outside of the case, my ear on them at different speeds
the phobya slim 180 are veryyyyyy quiet and make less noise at low RPM than the AP181.
The phobya fans can turn at lower speeds, even 5v. while the AP181 are minimum 500 or 700 RPM.
In the end i used the AP181, because at 700RPM, they make less noise than the phobya at full, while moving more air.
but if you want ultra silence with big exterior rads, 4-8 phobyas 180 @5v on minimum rpm are you best bet i think. (WAY cheaper than 20 noctuas too !)
if you go with 3 or 4 exterior 1080 rads, you may run them fanless
post pics if you do !
ah and for the pumps, the quietest solution is the Swiftech MCP655 PWM Pump (power from the power supply + PWM control from the motherboard with a special Y cable) + COV-RP450 Top (this one has a metal case all around the pump to further dampen the sound)
you would run them at low speed like 1,2 or 3. buy 2 and install them in series to have the pressure needed for all those rads.
you would have to suspend them to your case with elastics ( I used zip ties, works too) for max silence.
of course, waterblocks everywhere since your air flow would be very low in your case.
This would cost a lot of money yes, Welcome to the club !