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Fans spin, but not at boot, manual push is needed

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  • Fan
  • Computers
  • Boot
  • Components
Last response: in Components
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April 10, 2014 6:18:00 AM

Her are the facts:

While the computer is running my exhaust case fan will spin, IF I manually push it to get it rotating. If I start my computer and do nothing, I can see it budge, but it will not spin.

I know it's not the fan because I tried 3 fans and the same scenario played out 3 times. I'm thinking it's some kind of electrical draw issue because I can see the initial budge and the fact remains it will spin if I assist it to start.

Any ideas how to fix this?

More about : fans spin boot manual push needed

April 10, 2014 6:32:13 AM

Please list your hardware components including Case, PSU, MB and all other hardware connected to the PSU. Also explain how you connected the fans? Tell us what leads from the PSU the fans are powered by. It does sound like low voltage or that the PSU is not delivering enough power to start the fans.
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April 10, 2014 6:36:02 AM

Are your fans by any chance Fractal ones, set at 5Volts?

If so, then this is normal behavior for these exact fans, they need around 6-7 Volts before they can actually start themselves.
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April 10, 2014 6:36:06 AM

Do you have it plugged into a molex adapter? The molex may be on the 5V rail and not the 12v rail, and a lot of fans can't start without more than 5V. Though it should still turn on right at the beginning. Do you have any other molex plugs you can try?
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April 10, 2014 6:44:52 AM

motherboard = asus p8 z77-v lk
case = antec, case fans came stock with the case
power supply = roswell rd450 -2db

more facts that might help:

The intake fan and cpu fan are working as they should, no issues. I have the exhaust case fan connected to "cha_fan2". Motherboard "CHA_fan2" has 4 pins, however fan is 3 pin. I use the 3 pins furthest to the right. There is a guide/slot on those three pins, they fit with the fan's female connector. This is correct, to the best of my knowledge.

I hope that helps.
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April 10, 2014 6:48:13 AM

HiTechObsessed said:
Do you have it plugged into a molex adapter?


I don't know what that is. I'll look into it.

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April 10, 2014 6:51:56 AM

No, presently I'm not using an adapter.
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April 10, 2014 6:59:58 AM

Ok, ok, ok...

I think I might know whats going on... I only have 4 pins (not all 8) connected to the 12v EATX power connector, the one towards the rear of the motherboard. Does that mean I'm not receiving enough voltage towards the back of the board (where a lot of peripherals are)?

I don't know?
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April 10, 2014 7:11:33 AM

No, that's for the CPU power. The power for everything else on your motherboard comes from the 24-pin connector.

I'm not familiar with ASUS' BIOS, but I know they have good fan software. Have you tried using Fan Expert to adjust the speed?
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April 10, 2014 7:28:08 AM

Update...

The fans that came with the case are 3 speed. I had the exhaust fan set to low (as are the other fans, too keep the noise down, a priority for me). I switched it to medium. After 2 shut-downs and restarts the exhaust fan will start. I'd prefer to keep it on low, but I can live with medium until I figure out what's going on.

What does this mean?
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April 10, 2014 7:33:49 AM

Just adjust the speed in Fan Expert.
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April 10, 2014 9:02:23 AM

I suggest that you connect the fans via a 12v molex feed directly from the PSU. You do not want to use the MB fan control as yours are made to be powered from the PSU and adjusted by the 3 position case switch. I will bet that if you power them with a direct feed from the PSU all will work as intended.
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