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I have tow computer cooling fans in the case inside.
One of top is appearing in BIOS,other isn't appearing in Bios.
How can i know the number 2 fan is working in BIOS.
HELP!!!!

First check that both fans are getting power, i.e., do both fans spin? If so, then the problem is likely with the RPM sensor circuitry. BIOSs generally think a fan is not installed if it does not sense any RPM. Check that the pins in the fan connector are properly seated, and that the pins from the motherboard are not bent. If the motherboard has a 4pin connector but the fan has a 3 pin connector, check that the connector is on the correct 3 pins.

If you have tweaked the BIOS fan settings, the motherboard may be reducing the voltage to the fan to below its starting voltage. Try setting the fans to full speed to see if it starts (at which point the BIOS would see the non-zero RPM and assume a fan is connected.)

If you do not have a spare fan, try switching which fan is attached to which motherboard connector to see if the problem is with the connector or the fan.

Edit: From the pictures of this motherboard on NewEgg, it appears to have three 4pin fan connectors, labeled CPU Fan, Chassis Fan 2, and Chassis Fan 3. So, you may also want to try using different combinations of those 3 connectors.

Edit #2: Missed the Cha_Fan1 connector when I looked before, so that makes four 4-pin connectors.

MarkG509 wrote:

First check that both fans are getting power, i.e., do both fans spin? If so, then the problem is likely with the RPM sensor circuitry. BIOSs generally think a fan is not installed if it does not sense any RPM. Check that the pins in the fan connector are properly seated, and that the pins from the motherboard are not bent. If the motherboard has a 4pin connector but the fan has a 3 pin connector, check that the connector is on the correct 3 pins.

If you have tweaked the BIOS fan settings, the motherboard may be reducing the voltage to the fan to below its starting voltage. Try setting the fans to full speed to see if it starts (at which point the BIOS would see the non-zero RPM and assume a fan is connected.)

If you do not have a spare fan, try switching which fan is attached to which motherboard connector to see if the problem is with the connector or the fan.

I'm showing you a picture. This is my first time to build the computer...The fans's result in BIOS is N/A.



The picture you see in circle...

ilovecherlotte wrote:

I'm showing you a picture.

Try any of the other 2 fan connectors (Cha_Fan2 or Cha_Fan3), if they are not already occupied.

I assume your CPU heat-sink fan is connected to the connector labeled CPU_Fan, correct? Some BIOSs get annoyed if there's no fan connected there.

MarkG509 wrote:

ilovecherlotte wrote:

I'm showing you a picture.

Try any of the other 2 fan connectors (Cha_Fan2 or Cha_Fan3), if they are not already occupied.

I assume your CPU heat-sink fan is connected to the connector labeled CPU_Fan, correct? Some BIOSs get annoyed if there's no fan connected there.

You are right with my CPU connected to cpu_fan.
What wrong with this process?
it is fail to connect to cha fan3 and cha_fan4.
what can i do next?
But the fan is spinning...

ilovecherlotte wrote:

what can i do next?

Did you try connecting the fan that is not being detected to the known-good CPU_Fan connector to see if it still detected? And also connect the known-good CPU Fan to one of the Cha_Fan connectors to see if it is detected then.

What kind of fan is it. 2 pin, 3 pin or 4 pin. Doe's it have variable speed, etc, etc.
I doubt it's the fan header, but look in the manual for the pinout on the 4 pin connector so it corresponds to the needed pins on the fan. Especially if its a 3 pin one.
Also note that very slow spinning fans might not be detected and has to be set to ignore. I've had various slow fans like papst during the years and they usually are 2 pin and would needed to be set to ignore.

See this for instance.
http://www.interfacebus.com/ATX_Motherb ... inout.html

His BIOS might be giving him an error at POST because the fans are spinning below some arbitrary RPM threshold. Usually there is an option in the BIOS to disable fan speed monitoring.

ilovecherlotte: Can you take a picture of the error?

MarkG509 wrote:

ilovecherlotte wrote:

what can i do next?

Did you try connecting the fan that is not being detected to the known-good CPU_Fan connector to see if it still detected? And also connect the known-good CPU Fan to one of the Cha_Fan connectors to see if it is detected then.

another cha_fan is as same as nothing.
Im showing you a picture as below,

The Egg wrote:

His BIOS might be giving him an error at POST because the fans are spinning below some arbitrary RPM threshold. Usually there is an option in the BIOS to disable fan speed monitoring.

ilovecherlotte: Can you take a picture of the error?

I took a picture as above for more details.

Some case fans also do not have RPM monitoring so will not show up in the bios. If it only has 2 wires, the third yellow wire is usually the rpm monitoring wire and it will not show up to the bios.

Starfalcon wrote:

Some case fans also do not have RPM monitoring so will not show up in the bios. If it only has 2 wires, the third yellow wire is usually the rpm monitoring wire and it will not show up to the bios.

My two fans are from as same as brand...one is ok for showing in he picture. Anther isn't ready or has got a unknown problem....

Sounds like the fan may be defective.

Just to confirm a couple of things: If you connect the *other* fan to the same fan headers, it is detected, correct? And both of your chassis fans are 3-pin fans (no 4-pin Molex to 3-pin adapters or anything like that, right)?

I also suggest plugging a different fan into the same header and seeing if it detects the RPM. Either way, if the fan is still working it's not the end of the world.



You could either disable the Q-Fan control, or set that particular fan's low limit to "Ignore". If you're worried about it doing something to the motherboard, use a 3-pin to 4-pin molex adapter.

Nothing showed!

just brew it! wrote:

Sounds like the fan may be defective.

Just to confirm a couple of things: If you connect the *other* fan to the same fan headers, it is detected, correct? And both of your chassis fans are 3-pin fans (no 4-pin Molex to 3-pin adapters or anything like that, right)?

I'm using this fans as below picture...
(I brought it for more than three years.)

The Egg wrote:

I also suggest plugging a different fan into the same header and seeing if it detects the RPM. Either way, if the fan is still working it's not the end of the world.



You could either disable the Q-Fan control, or set that particular fan's low limit to "Ignore". If you're worried about it doing something to the motherboard, use a 3-pin to 4-pin molex adapter.

I'm showing you my BIOS setting as below.