ga-z68x-ud3h-b3 i5-2405s cpu fan does not start

[deycks]

I just built a pc with the ga-z68x-ud3h-b3 mother board and i5-2405s.  The i5-2405s uses only 65 watts. When I booted the pc I got to the bios splash screen but the cpu fan did not start. Should the fan start immediately? How long should I wait for the fan to start?

[Rolo42]

It doesn't always start immediately.

Ensure the fan mode is set correctly in BIOS (PWM for 4-pin, Voltage for 3-pin fan connector).  If you have it set to silent, it'll spin as little as possible.

[Dark Mantis]

Don't forget if the fan speed is governed by the BIOS it will wait until it hits a temperature level before it fires up. The mass of the heatsink will act as a cooler for several seconds before it needs active cooling instead of passive.

[deycks]

You said it would take a few seconds for the fan to start. I believe I waited 30 seconds but it did not start. The CPU chip is an i5-2405s which only uses 65 watts.   I think the cpu was up to 35 degrees centigrade when I looked at it in the health section of the bios. How hot can a cpu chip get without damage? How long can I wait before causing damage? I changed the bios cpu smart fan control to disabled and the fan runs but is noisy.