cpu fan not spinning

[NinjaPenguin1]

I just screwed my laptop back together after replacing the thermal paste.I booted into windows like normal and launched valley benchmark and hw monitor to check my new temps.
I started the benchmark and i saw that the temps went up pretty fast, so i checked to see if the fan was spinning. It wasn't.
I tried restarting many times, but nothing worked. I noticed when looking at the fan while booting it looked like it tried to spin up, but couldn't make it.
So i unscrewed the laptop again and tried connecting the fan power to a 5v usb. The fan started spinning.
Do you think there is something wrong with the mb fan connector?
Or something wrong with the third pin on the connector?

Hmm, i'm confused. It just randomly started spinning again.
Anyone have any idea why this is happening?

 

[jarotech]

Hi, what is the make and model for your laptop?

 

[NinjaPenguin1]

Hi, what is the make and model for your laptop?

It's an acer aspire 5750g

 

[jarotech]

On which pin did you put the 5VDC, the first pin or the middle one?

 

[NinjaPenguin1]

On which pin did you put the 5VDC, the first pin or the middle one?

I put it in the first red pin.

 

[jarotech]

Maybe it's the driver who control the fan who is corrupt.