Low or no voltage for the two fan connectors on the motherboard. Fans will not run when attached. Have to use a direct connector from the power supply. All voltages from the power supply check okay.

Did you check the fuse and the voltage at the supply side of the relays? How about the wiring and particularly the connectors? Also, it is not unusual for a new temperature sensor to be faulty - try jumping the contacts in the sensor connector to see if the fans activate.

There are two power connectors on the motherboard one twenty four pins and the other is an eight pin connector. The symptom you described normally happens when we forget to connect the 8 pin connector. This power is converted on the motherboard to the processor core voltages and port power voltages. So it is situated physically nearer to the processor and ports. Make sure you have a power supply that has the two connectors and also that you have connected both. The 8 pin connector has only black and yellow wires. Hope this helps.

Are you seeing this error on a system you built or a pre-built system? If it is a pre-built system, check that the fans are running. Next check where the fans are plugged in, the CPU fan must be connected to the CPU fan connector on your motherboard. The chassis (rear case fan) only needs to be connected to the motherboard if you want the monitoring/PWM (modulated fan speed) option. If your CPU fan is powered directly from the power supply, change this.

If this is a system you built or recently updated the case, check your fan power connections, as above. Next check the fan speed. My ASUS board will give the "CPU fan not detected" error if the CPU fan speed is too slow. A different CPU fan will solve the problem. (I got my fan with the CPU; it works fine.)

I hope this helps. Please add a comment with more information about your system for more assistance.

Cindy Wells

first change u r smps if no diffrence problem is same then disconnect all chassis fan one by one and check voltage again.

Remove Power Supply
1 . Shut down your computer and unplug the power cord and all cables connected to the system.

2 . Open the computer case and disconnect all power connectors from the motherboard, drives, cards and fans.

3 . Remove the four screws that secure the power supply to the case. These screws are located on the back of the computer case, at each corner of the power supply.

Wire and Start Power Supply
1 . Switch the power supply to the "Off" (sometimes "O") setting.

2 . Insert the end of one wire from a single pole, single throw (SPST) switch into the green wire of the ATX power connector (the largest power supply connector).

3 . Insert the end of the other wire from the SPST switch into the black wire of the ATX power connector. If your power supply has two black wires, connect the SPST to the black wire directly beside the green wire.

4 . Wrap electrical tape around the ATX power connector and wires from the SPST switch to hold them in place. Make sure there is no exposed copper or silver wire from the SPST switch wires.

5 . Turn the SPST switch to the "Off" position, if not already set. Plug the power supply into the wall outlet and switch it to the "On" (sometimes "I")setting.

6 . Connect any other computer components that you wish to operate without the motherboard, such as fans, drives or cards. Turn the SPST to the "On" setting to activate the power supply.


Hope the above information will be helpful to you.
Thanks.

Motherboard fan connectors typically use a small 3-pin which looks like this:
the left connector is a female connection (the side with 3 holes) the middle and right are male connections, has 3 metal pins:

• Black: GND (ground)
• Red: +12VDC or +5VDC (12V or 5V DC - direct current)
• Yellow: Tachometer signal (used to read fan speeds)

NOTE: Wire color may vary, and some fans or motherboards may control fan-speed.

Some fans use a 4-pin connection, which is generally a CPU fan connector but not always:

This pictures a 4-pin connection, but may look different from other 4-pin connections because the wires are covered in a black sleeve, which keeps them safe from harm and to reduce potential negative affects on airflow created when there are lots of loose wires inside a computer case.


This photo shows a 4-pin connection attached to a motherboard next to a 3-pin connection in a motherboard. While it is not recommended in the case of the CPU's fan, in the case of other internal case fans with a 4-pin connection, it is possible to plug them into a 3-pin connector of the motherboard, but the ability to control fan speed, which is controlled in the 4th pin will be lost.

Though sometimes computers have a way of controlling fan speed on a 3-pin or 4-pin connection even without the 4th pin, such *** voltage regulation and reading tach. feedback. These things are typically things a general user doesn't need to worry about unless their computer is running particularly hot and causing trouble.

In which case, it might be worth investing some money in a fan controller, which takes a power connection, several fan connections (varies based on the controller you get) and gives you the ability to control fan speed externally on your computer case. My controller has nice dial knobs, though some "fancy" controllers have a display and up and down buttons. (Fan controllers would be at your own discretion in terms of price, you can get them cheap all the way up to seemingly ridiculous expensive)

In the event of not having enough 3pin or 4pin connections on a motherboard, it is still possible to add case fans by way of 4pin molex connections:

A female molex connection


A male molex connection

Some case fans run exclusively through these connectors, others have a combination of a 3pin (or 4pin possibly, though I've never seen this combination) and a 4pin molex connector. In this case, the molex connector can connect directly to a cord from the power supply and run the fan. It is possible to run case fans without having them connect to the motherboard at all! Which makes it possible to connect more fans, with less available connections for your fans on your motherboard.

If a fan is a certain connection (any of the 3) and you need to convert it, for example:

• a 3pin to a 4pin molex because your motherboard doesn't have enough 3pin connectors for all your fans,
  

adapters are available to change one type of connection to another, at many online retailers (such as newegg.com, amazon.com, or other electronic supply retailers) and some retail stores, Best buy might have something, though you'd have a safer bet at a store like Micro Center which is more specialized for PC building or an alternative PC/electronic store.

To ensure you solve your problem, just be sure to familiarize yourself with the motherboard you are planning on buying (or have) and the fans you plan to have inside your computer. It can be a bit more work to check the specs on the fans and motherboards, but a little work saves hours of headache later.

According to the manual your Motherboard supports two case fans. You can use either of these pins setups. For your motherboard you have three pins with the third pin ( CLOSEST TO THE CPU) controlling the rotation of the fan. For your two pin fan put the black ( ground ) wire of the two wires on the pin FARTHEST from the CPU.
Note: Manual says the fans should be a max of 350 Ma.

For more information see your manual or look here for a on-line manual.

http://www.manualnguide.com/dl/9354/

Good Luck

You are drawing too much current from the power supply with the current hungry fan.Try using a different fan that draws less power on start up. Or use a limiter to lower the input voltage draw on start up. These are usually found in fan speed controls You could also use a voltage dropping adaptor like the one use to quite fans down . They drop the 12 volt voltage to 7 volts by connecting the two voltages usually found on the power connector 12v and 5v and and adding them together getting a 7 volt output. You can also try connecting the fan directly to the power supply and avoid using the motherboard connector.The problem with this is you will not get use of the speed controling sensors used in the motherboard connections. Hope this helps you with your problem.

If your cpu fan has a 4 pin connector & your mb has a 3 pin you can still use it. Just leave one pin exposed. The extra pin is for a speed control sensor that not all mb's support. The chassis fan has a different connector on the board marked "cha fan". This one is a 3 pin connector. Most of the asus boards have 1 of these. If you wish to run more than one you can either buy a "y" adapter that allows you to connect 2 fans to 1, you could use an extra 4 pin molex to power an extra fan but that would give you no control over the fan, or you could buy a fan controller and hook all your extra fans to it. Hope this helps & please take a moment to rate my solution fixya. Thanks.

the problem is your power supply, since the power supply have differrent output voltage there is 12volts, 3volts and so on. the 12volts output voltage is not giving enough power. you can determine this by detaching the 20pins from your motherboard coming from the power supply then power-on the power supply then use a jumper wire insulated but scraped both ends (conductor visible) then connect it to the green connector and the grey connector if the fan of the power supply doen't rotate then you 12volts output voltage is busted.