R720 Fan work at 100%

server fan`s work at 100% speed.

i turned off system and disconnect power - didn't help

I updated idrac to latest version - didn't help

now i can`t reser IDRAC config, because - the server is in another city, and it can only be turned off at night when no one is working - but then no one will configure it

Once I managed to reset the settings, and the fan speed was normal, but then I changed something in the BIOS performance settings - and again the speed became 100%