Quote Originally Posted by vipertwo View Post
My case is such that I can get close enough to read all the labels on the motherboard so I'm sure about which header is which.

Anyway I investigated a bit more and discovered a curious thing -- I do see an RPM reading for some fans but not others: the RPM sensing seems not to be working for all kinds of fans at low voltage. In particular I have some Noctua fans which are not sensed correctly.

Rear Fan header at 5.55V (CPU idle with case lid off):
Scythe 80mm (DFS802512L from Ninja Mini HS): 1134 RPM
Sharkoon 80mm golf ball: 367 RPM
Noctua NF-R8 80mm: zero RPM reading (but it is spinning)

Rear Fan 2 (Aux): 11.95V
Scythe: 2063 RPM
Sharkoon: 778 RPM
Noctua: 1909 RPM

Has anyone seen this before?

It's not an issue with one particular Noctua fan -- I have several of them and they consistently give an RPM reading with the Aux header but not the Rear Fan header. I won't be changing the Noctua fans though -- they are really nice and quiet .

CPU fan = fan 1, Rearfan2/Aux= fan 2, Rear Fan = fan 4, so I guess the front fan will turn out to be fan 3.

It would be nice to know what all the temp readings are in the sensors output.
Hmmm. The fans all read for me so I'm not sure what's going on.

temp1_input = cpu on-die sensor (NOT the core temps)
temp2_input = motherboard (the asc7621a chip itself)
temp3_input = memory (between the 2 sets of dimm sockets)

The rest are assigned by various peci settings but really are not much use. Use the coretemp driver to get the individual core temps.