P55A-UD3 cpu fan spins up randomly

[jblang]

I just completed my new build using a GA-P55A-UD3 motherboard about a week ago. I've noticed the CPU fan will spin up to full RPMs for about a second and then spin back down, seemingly at random. I haven't noticed any stability issues with the build or any other problems besides this. There is no corresponding spike in CPU usage or temperatures that goes along with the fan spinning up. I am not overclocking and have the optimized defaults loaded in BIOS, and I'm using BIOS revision F4.

Has anyone seen this? Do you have any thoughts on how to fix it? I don't know if it's worth returning the board over but it is sort of annoying.

Relevant build details:

GA-P55A-UD3 Mobo
Core i5-750 CPU
4GB Kingston HyperX 1600 Memory
Thermaltake Silent 1156 CPU cooler

[Pottypete]

Hi
That is normal, as the cpu temp rises so will the fan speed,
It's auto sensing temps,
Cheers

[jblang]

As I said in my original post, the temp does not rise when the fan spins up.  The processor is completely idle, and I've watched it using HWMonitor and the CPU temp is not spiking when the fan spins up.

[Pottypete]

Hi,
Have you the latest bios for the mobo?
Cheers

[jblang]

Yes, F4. F5a is in BETA, released yesterday but I don't really want to install a beta BIOS.

[cpharris]

Think this is pretty normal. My computer (P55M-UD2 + Core i5 570) does exactly the same in idle. Spins up for a couple seconds, then back to normal. I believe it is something to do with the core temperature reaching a point where the fans spin up to reduce the temp. Even though you can't actually see any temp or CPU 'spike'...

My theory is that the temp sensors used on the i5 and i7 cores are pretty rubbish at detecting low temps (it's a well known problem with the sensor types), but much more stable at high temps. If I watch my core temps at idle they jump around much more than at load. I guess this may be triggering the fans.

Either way it's a common condition!