Gigabyte PWM System fan Control

[fadsarmy]

Just bought a gigabyte mobo from scan (GA-MA770-UD3). Bios provides fan control for only one System fan via PWM. There is also an option to enable siren if this fan fails. I have a 4-pin PWM fan plugged into this PWM System fan connector. When I cold start the pc the fan does not spin for around 5-10 minutes until the pc warms up and until then it beeps.

I have the same fan on a different Gigabyte mobo which does not behave like this. It starts spinning straight away and therefore no beeping.

The guy at Scan said this is normal behaviour and advised me to switch off the fan fail warning, but I refuse to accept this.

Any comments.

[Oldjim]

I had a similar problem with my Gigabyte motherboard and there is nothing in the manual about it.
However a bit of playing produced the following result with the system fan controller.
With a 4 pin fan (the Intel CPU cooler fan as I wasn't using it) it did start but at very slow speed. I then tried a 3 pin 120 mm fan and it didn't start but flicking the fan blades started it but very slowly.
The conclusion I came to is that the speed is automatically linked into the motherboard temperature even though there isn't a motherboard fan (if there was it would be very small and would spin up on a fairly low voltage) and nothing in the bios setup will change it unless I disable smart fan which will affect the CPU fan. There doesn't seem to be any method of setting a minimum speed/voltage for this.

[fadsarmy]

There should be a minimum voltage, when system is cold, supplied to the fan to keep it spinning and prevent the beeping. The cpu fan doesn't stop spinning so why should this.

[Oldjim]

It all depends on what they have set the minimum voltage to. I couldn't find any way of changing this.
Different fans require different minimum voltages to start and the system fan controller is probably designed for a 32mm or 40mm fan which is more likely to start with a very low voltage.
Note that in my test the 120mm fan wouldn't start but the the CPU fan which was a lot smaller would