Hello, long time lurker first time poster.
Just got my LB4M off ebay with only 1PSU. I plugged it in and was literally blown away how loud this sucker was. Around 67-69dB with a rudimentary phone app taking measurements. As someone mentioned before the loudest component is the PSU. I was really disappointed that this thing is louder than a Dell R715! I got to it and removed the PSU cover which had seized up screws so I had to drill a few out and swapped in quieter Evercool fans from here
Evercool EverCool 40mm Ball Bearing Case Fan FAN-EC4010M12CA - Micro Center
Now it reads 42-44dB! Perfectly comfortable and just a hair louder than my Dell R730. The temps are only a little bit warmer around 45c but so far it's working with the two Brocade 1020s. +
My only issue is after setting jumbo frames everywhere between the switch, vmware, and the NICs in windows I'm only able to sustain about 4.6-4.7Gbps using Lanbench between two VMs on seperate hosts. Netio depending on the packet size spikes up to 6.7Gpbs but the only thing I haven't messed with are C states for either hosts.
Thanks for all the great info in this thread!