I've been experimenting with the system fan connections, initially with the intent of temperature controlling two front PWM (4-wire) fans on my Lian Li case so that it remains quiet unless I load it up.
I thought it worth mentioning that the four system fan headers on this board seem to behave differently.
I have four identical PWM fans so I was able to test all four headers independently or together.
Connected to SYS_FAN1 header, a fan seems to run quite slowly, (say, 700rpm at ambient) although it is controlled with temperature.
Connected to SYS_FAN2 header, a fan runs about twice as fast (say, 1400rpm at ambient) also controlled.
Connected to SYS_FAN3 header, a fan runs the same as SYS_FAN2.
Connected to SYS_FAN4 header, a fan seems to always run at full speed, uncontrolled.
It seems odd that they are different.
I'm using BIOS F5 at present. Setting system fan mode to SILENT or NORMAL etc does seem to vary the speeds of Fan1,2 and 3 proportionally, but they remain different.
Disabling fan control entirely makes them all run at full speed, and swapping them around proves that it's not the fans that are different.
Does the system expect a different type of fan on each header, or perhaps it is applying a different slope PWM to each of the headers for some reason?
Or maybe even a BIOS bug ? It's all a bit strange.
Of course I can persuade the two front panel fans to run at the same speed by bodging them both on to one header circuit, but I'd still like to understand what the board is supposed to do.
I note that the pin connection descriptions on page 27 of the manual vary slightly between the four headers, but this doesn't help at all; I don't know whether that may even be a typo.
I thought it worth mentioning that the four system fan headers on this board seem to behave differently.
I have four identical PWM fans so I was able to test all four headers independently or together.
Connected to SYS_FAN1 header, a fan seems to run quite slowly, (say, 700rpm at ambient) although it is controlled with temperature.
Connected to SYS_FAN2 header, a fan runs about twice as fast (say, 1400rpm at ambient) also controlled.
Connected to SYS_FAN3 header, a fan runs the same as SYS_FAN2.
Connected to SYS_FAN4 header, a fan seems to always run at full speed, uncontrolled.
It seems odd that they are different.
I'm using BIOS F5 at present. Setting system fan mode to SILENT or NORMAL etc does seem to vary the speeds of Fan1,2 and 3 proportionally, but they remain different.
Disabling fan control entirely makes them all run at full speed, and swapping them around proves that it's not the fans that are different.
Does the system expect a different type of fan on each header, or perhaps it is applying a different slope PWM to each of the headers for some reason?
Or maybe even a BIOS bug ? It's all a bit strange.
Of course I can persuade the two front panel fans to run at the same speed by bodging them both on to one header circuit, but I'd still like to understand what the board is supposed to do.
I note that the pin connection descriptions on page 27 of the manual vary slightly between the four headers, but this doesn't help at all; I don't know whether that may even be a typo.
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