On start-up CPU fan wobbles, then stops...?

[bovinda]

On brand new build, when I power-on the CPU fan starts for just a second (meaning it wobbles) then stops and won't start, unless I manually spin it (yes, use my fingers to get it going), then it takes off and is fine. What's up with that?

I'm using the stock fan on the Coolermaster Hyper 212+ cooler, on a Gigabyte P55 UD2 mobo, with an Antec CP 850 power supply. Everything else seems to start up fine.

Do I need a new fan? Is this something I can affect in the BIOS somehow...? Like is the fan not getting enough voltage? But isn't that weird that the CPU fan would have that?

Not sure what to do next...any and all help greatly appreciated!

And yes I've got the CPU fan hooked up to the proper pins on the mobo...

 

[cmdrdredd]

Try removing the FAN from the MOBO connector and plug it directly into the PSU via a molex connection. This might help as some motherboards have a limited amount of power available and it might not give quite enough juice to spin it up from a stop. This will also tell you if the fan itself is bad.

If you don't have a fan adapter you'll need something like this http://www.newegg.com/Product/Produc...-248-_-Product

It even has a plug that goes to your motherboard to monitor the fan speeds, but draws power directly from the PSU and not through the mobo.

 

[lothar]

My current system does something like that, but a little different.

When I power-on the CPU fan starts for a second, then completely stops for about 2-3 seconds then starts spinning fine.
I don't need to resort to manually spinning the fan but it's something I've noticed over the past year or two.
Of course this system is 7 yrs old and will be turning 8 next spring so naturally I attribute that to age (or maybe dust buildup? haven't opened case in over a year).

I can't wait to get rid of this system.

 

[bovinda]

Try removing the FAN from the MOBO connector and plug it directly into the PSU via a molex connection. This might help as some motherboards have a limited amount of power available and it might not give quite enough juice to spin it up from a stop. This will also tell you if the fan itself is bad.

If you don't have a fan adapter you'll need something like this http://www.newegg.com/Product/Produc...-248-_-Product

It even has a plug that goes to your motherboard to monitor the fan speeds, but draws power directly from the PSU and not through the mobo.

Thanks for the suggestion, I'm heading over to a Frys right now, and I'll see if I can pick one of those up. If not, I'll order it from the Egg. I'll report back.

 

[aigomorla]

isnt that the normal function of how a PWM fan behaves?

Plug your 4 pin pwm fan into a 3pin fan port and see if u have the same problem.

 

[bovinda]

isnt that the normal function of how a PWM fan behaves?

Plug your 4 pin pwm fan into a 3pin fan port and see if u have the same problem.

So I got over my fear of frying the CPU and just let it start up. It turns out the CPU fan starts after about 6-7 seconds, and then everything boots up normally. (So I doubt it was me manually spinning the fan that started it after all.)

So...is that normal for a PWM fan? (If so, anyone know why? For comparison, the case fans start instantly.) I don't have previous experience with PWM fans. I think I just got afraid that the CPU was going to cook if the CPU fan didn't start right away.

 

[aigomorla]

PWM .. pulse with modulation.

Basically it pulsates the voltage as load is applied to the cpu.

If it bothers you, switch the fan header over to a 3prong one.
It should fit as PWM is backwards compatible.