C2550D4I Smart Fan setting explanation?

[ZdendaV]

Can someone please explain the Smart Fan Settings in BIOS under the H/W monitor tab?
There are 10 manual speed setting:
Setting RPM
1 300
2 500
3 600
4 700
5 900
6 1000
7 1100
8 1200
9 1400
Full 1500

And then there is Smart Fan:
see attachment

I would like to know which sensor (CPU, MB) controls which Fans (Front, Rear, CPU) and how to set it that for instance the CPU is 40C then the CPU Fan has 500RPM, when 50C then 1000RPM and so on.

[ZdendaV]

Re: C2550D4I Smart Fan setting explanation?

It seems it was able to figure it out using trial & error.
It seems all fans are controlled by the CPU temperature.
Each Duty cycle corresponds to a temperature:
30% 40 C
...
100% - 90 C

The temperatures and duty cycles are "hardcoded", you can't set duty cycle to 20% or 40% or the temperature to 43 C or 52 C.

Because I consider everything beyond 65 C way too high, I've set it this way:
45 C 30%
50 C 55%
55 C 65%
60 C 80%
65% and higher 100%

It's not ideal but I think it's the best I could get ...

[ZdendaV]

Re: C2550D4I Smart Fan setting explanation?

Here is some follow up.
I've set the minimal fan rpm a little higher to keep my HDDs cool:

Duty1 55%
Duty2 65%
Duty3 75%
Duty4 85%
Duty5 100%

Temp1 45 C
Temp2 50 C
Temp3 55 C
Temp4 60 C
Temp5 65 C

and I encountered a nasty bug.
After some random time the fans get reset to the lowest speed.
It seems, I'm not the only one: https://bugs.pcbsd.org/issues/16028