New CPU fan not working

  • Thread starter Thread starter momx5
  • Start date Start date
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momx5

When I booted up my computer the other day, I got the message
"CPU fan has failed" and it shut back down. Today I bought a
new fan, and installed it. It still does not work! :crybaby: My
husband took the old fan and hooked it to a battery and it worked just
fine, it just won't work in the computer. Someone please tell me what
is making the fan not work...I work from home and can't function
without my computer.
 
momx5 said:
When I booted up my computer the other day, I got the message
"CPU fan has failed" and it shut back down. Today I bought a
new fan, and installed it. It still does not work! :crybaby: My
husband took the old fan and hooked it to a battery and it worked just
fine, it just won't work in the computer. Someone please tell me what
is making the fan not work...I work from home and can't function
without my computer.
Click to expand...

The fan appears to be OK, so of there another 3 pin connector on the
motherboard you can plug it into try it - there are usually a few. If so and
if it works in there, I would go into the BIOS and disable the shutdown on
CPU fan failure and enable the shutdown on CPU temperature setting -
assuming you have these settings. If the fan doesn't work on another (or
any) of the motherboard connectors, then either the motherboard is failing
to power these connectors or the power is insufficient to start the fan
spinning in which case - give it a good clean and see if that helps (might
be that the test battery might have had a higher ampage - more power at the
same voltage).
 
momx5 said:
When I booted up my computer the other day, I got the message
"CPU fan has failed" and it shut back down. Today I bought a
new fan, and installed it. It still does not work! :crybaby: My
husband took the old fan and hooked it to a battery and it worked just
fine, it just won't work in the computer. Someone please tell me what
is making the fan not work...I work from home and can't function
without my computer.
Click to expand...

OK, this cable is what you want. As far as I can tell, there are
two cable assemblies in this package, which is hard to see in
the picture.

http://www.newegg.com/Product/CustratingReview.asp?item=N82E16812105007
http://images10.newegg.com/NeweggImage/productimage/12-105-007-01.JPG

That cable consists of three connectors. A female fan header, a male
fan header, and a four pin Molex disk drive connector. The cable
draws power for the fan, from a disk drive cable. So if the motherboard
header power source is burned out, that cable can bypass the power
problem, and allow the fan to run.

The female fan connector has the RPM wire on it. When you plug in the
female connector, to the CPU fan header, that is how the motherboard
will get the RPM signal that tells it the fan is spinning. So that still
has to be plugged in.

This is essentially what the cable does.

Molex 1x4 Male 3 pin (plug fan
into this)
12V --------------------------------------- Fan +12V
GND -------------------------------+------- GND
GND --X | +---- RPM
5V --X | |
| |
| +---- RPM
+------- GND
X-- Fan +12V

Female 3 pin (plugs to
CPU_FAN motherboard header)

In the above figure, I rearranged the pins on the fan connectors, to make
it easier to see the wires. The fan pinout is *not* as shown above. Check
the motherboard manual, to see the actual order of the fan pins.

Second note, I drew the wire assembly, as I see it in the Newegg picture.
In fact, the GND wire running between fan headers is not needed. I have
one cable assembly like the above, that has a single white wire running to
the female connector.

Third note, there are other versions of this assembly available. There
is one that has two Molex 1x4 connectors on the left hand side of the
picture. That one allows these adapters to be "stacked" or "daisy chained"
so you don't lose the use of the Molex drive connector. If the
computer in question is low on Molex drive connectors (say the computer
is a Dell/HP/Gateway, and there happen to be no spares), you can
buy a "Y" cable for disk drive connectors, and that will give a second
connector for use with the above cable.

http://www.newegg.com/Product/Product.asp?Item=N82E16812119008
http://images10.newegg.com/NeweggImage/productimage/12-119-008-01.JPG

So the purpose of the above fan adapter cable assembly, is to:

1) Power the fan from a disk drive connector.
2) Feed the RPM signal to the CPU_FAN header.
3) To be used, if the power dies on the CPU_FAN header.
4) Or can be used, if a fan draws more current than the fan header can
provide. For huge fans drawing 1 amp, an adapter like this will
protect the fan header from burnout.

HTH,
Paul
 
When I booted up my computer the other day, I got the message
"CPU fan has failed" and it shut back down. Today I bought a
new fan, and installed it. It still does not work! :crybaby: My
husband took the old fan and hooked it to a battery and it worked just
fine, it just won't work in the computer. Someone please tell me what
is making the fan not work...I work from home and can't function
without my computer.
Click to expand...

It means the fan RPM signal was too low (Or not read). The
fan might work but spin too slow now due to a progressive
failure of the bearing. Similarly, the new fan might also
spin too slow to be detected properly- some motherboards
can't properly detect very low RPM fans, OR it could be that
the replacement fan does n't have an RPM signal output (3
wires going to the fan header on the motherboard).

It might be possible to enter the bios and turn off that
shutdown-on-failed-fan setting, though ideally you'll supply
us with more info about which of the above possibilities
seems probable, or if none of them, other related info to
help determine the cause.
 
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