My understanding is that they run hotter and do not have the same efficiencies as other PSUs, which is odd because servers are extremely common.
Run hotter - yes. The HP supplies will get uncomfortably warm to touch @ full load but that is normal. They are made to run like that for years.
As for the eff -- they were made in 80Plus ranging from Bronze (pretty poor) and currently up to Platinum (excellent). Prices for the PSU's reflect that: 80Plus Bronze ones can be had for as little as $15-20 and prices go up from there.
I wondered what others do for noise..
At first, I had it in the laundry room in my apartment.... On top the excessive heat and noise, the maximum I got was 9.259 Th/s.
It was becoming unbearable so I took it out to the balcony, put it inside my small bedside table with shelves (the air inlet facing the inside and air outlet facing the open side, then covered the open side with a pillowcase. Balcony is covered space to not worried about snow falling and melting on it.
Sorry I was more concerned about what to do with the monster than collecting stats so no rpm and temp information from before.
It's -8c out there and my S9 is running at 83c. Fan speed came down from about 4000rpm fan3 and 6000rpm fan6 to 3,960rpm fan3 3000rpm fan6 .
Highest Chip temp 83 = 28c
Currently mining at 13TH/s and more sometimes.. I saw the stats on my pool dashboard reach 14.78 Th/s at one point.
My project this week is building a sound insulated box with in and out vents. then I will start worrying about keeping it cool in summer. (I suppose a topic for new thread)
Is anyone working on something similar? Seems small sound insulated server racks cost more than the machine itself.