My motherboard has a problem the cpu fan spins only in 1 second then it will turn off but the power supply is ok. what it does mean?

take a A+ cert course then tell this fib again.?

An LED can glow at 2vdc, tells you nothing!
only that some weak power is present, nothing more...!
learn that in electronics.
it can fail all theses ways.
good
bad.
weak
intermittent.

the PSU tests are covered here, take a volmeter
not some LED on a stick or parts glowing.
got 50 years of on the job doing this, from DC to daylight, from MIL to you name it.

http://pcdied.com/black-screen.html

If you are testing the motherboard by removing items plugged into it, remember to leave the CPU Heatsink on if the CPU is still in the socket otherwise the CPU will overheat in seconds or minutes and could be damaged.

If you power on the system, do the fans spin? such as the CPU heatsink fan? If no fans are spinning that are connected to the motherboard, see if the fan is spinning inside the power supply using a flashlight if needed. If not, try a known good power outlet or different plug on your surge bar or a new surge bar.
Even if the power supply fan is spinning, the power supply could be faulty. Borrow or buy one that matches the current wattage written on the side (ie: "output 350W")

Post back here with more info or if anything of this sounds like the issue you are having.

A) With great tact and diplomacy;
Do not refer to a Personal Computer as a CPU.

CPU = Central Processing Unit.
Another term is Microprocessor, or simply Processor for short.
CPU = Processor

B) Because of the method you used to refer to the Computer, I do not know if you're talking about; the PROCESSOR did not start, or the Computer.

C) If I we are to believe this is a reference to the Computer;

1) Check the Power Supply voltages,
OR
2) Substitute the Power Supply; with a KNOWN to be working, Compatible power supply, for a temporary test unit.

Why?
A) If ALL the LED lights were on at once, they would use less than 1 Watt of power.

B) EACH fan uses 2 to 3 Watts of power.

C) A typical Processor can use 51 to 125 Watts of power.
Just depends on what Processor it is.

A Power Supply with a weak voltage power rail, will not have enough power to turn the Processor on.

However I am still confused by the statements;
1) "CPU did not run"

Does this mean the COMPUTER did NOT turn on, which implies the Power Supply did not turn on;

OR,

Does this mean LED lights came on, fans may be spinning, but Windows does not load?

2) "I can't find any signal on my Computer........"
Signal = Voltage.

To see if there were voltages going through the motherboard, you wouldn't be posting on here. You would know how to take a multimeter, and test them.

Means to me you see No Signal on the monitor.

D) Are you FOLLOWING Anti-Static Procedures?

E) Power Supply voltages prove to be good, or you are using a KNOWN to be good, Compatible power supply?

Disconnect EVERYTHING from the motherboard.

NO cables to the motherboard, EXCEPT the 24-pin ATX main power cable,

http://www.playtool.com/pages/psuconnectors/connectors.html#atxmain24

[NOTE* Color of connector does NOT matter ]

,and the 4-pin ATX +12 Volt power cable,

http://www.playtool.com/pages/psuconnectors/connectors.html#atx12v4

Disconnect the data cable AT THE motherboard, for the Harddrive, and optical drive/s. (CD/DVD drive)
Disconnect the power cables to them also.

Disconnect ANY USB front panel cables.

LEAVE processor fan wire connected to motherboard.

You want the Processor, finned Heatsink sitting on it, and the Processor fan.
ONE stick of Ram Memory in Slot 1. (DIMM 1)

Leave graphics card in, IF used; or monitor is connected to the VGA port on the motherboard. (D-Sub connector)

Turn the Power Supply on.
You should be able to bring the BIOS Setup screen up.

If no, consider the motherboard to be bad.

http://www.msi.com/product/mb/G31M3-L-V2---G31M3-LS-V2.html

http://www.newegg.com/Product/Product.aspx?Item=N82E16813130217

Post back in a Comment, as to the information I need.
CPU = Processor
PC = Computer, or just use Computer.

Regards,
joecoolvette

PSU IS OK? You're sure? You tested the 3 main voltages coming out?

DON'T rely on; "The LED lights are on, and the fans spin, so therefore the PSU must be good.

1) If ALL the LED lights were on at once, they would use less than 1 Watt of power.

2) EACH fan uses 2 to 3 Watts of power.

3) A typical Processor uses 51 to 125 Watts of power.

With a Power Supply that has a weak voltage power rail, you will see LED's light, and fans spin; BUT not enough power to turn the Processor on.

Power Supply also needs to be plugged into motherboard to test, because you need a Load on the Power Supply.

PSU is KNOWN to be good? I mean KNOWN.
Not, "It's brand new so I know it has to be good"
Okay, moving on.

CPU OK?
How did you test it? Install on another working motherboard?

Are the Electrolytic Capacitors on the motherboard good?

http://capacitorlab.com/visible-failures/index.htm

http://www.youtube.com/watch?v=Lut7MX5Dd_A

Capacitors on the motherboard are used as Filters, and Voltage Regulators.
The ones used as Voltage Regulators are in the Motherboard Voltage Regulator Circuit,

http://www.hardwaresecrets.com/article/616

Part of what the Motherboard Voltage Regulator Circuit does, is to regulate voltage for the Processor. (CPU)

The CPU MUST have a steady, 'clean', supply of voltage, and it MUST be kept within the Processor's voltage tolerance range.
Too much, or too little, and the CPU shuts off. BIOS turns it off.

(CPU stands for Central Processing Unit. Another term used is Microprocessor, or simply Processor for short.
I know you are aware, just posting for all those who read the solution in the future)

http://downloadmirror.intel.com/15140/eng/D945PLRN_ProductGuide02_English.pdf

[Better motherboard due to the Intel Q965 motherboard chipset,

http://www.ebay.com/itm/INTEL-DQ965GF-CORE-2-DUO-LGA775-SOCKET-P-4-MOTHERBOARD-I-O-FACEPLATE-INCLUDED-/290863623024?_trksid=p2047675.m1850&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%26asc%3D11%26meid%3D5685984037376928917%26pid%3D100011%26prg%3D1005%26rk%3D1%26sd%3D330632928551%26

http://en.wikipedia.org/wiki/List_of_intel_chipsets#Core_2_chipsets

Scroll down to Q965 in left column ]

For additional questions please post in a Comment.

Regards,
joecoolvette

Not sure just what you mean. If your computer is plugged into the wall and the power is turned on, the power supply should be on and the cooling fan turning. Also, the CPU fan should be turning and the hard drive should spin up.
Note that the power supply is the main component that must be supplying the power. If you don't hear or see the fan turning in the power supply and the little power light on the front of the computer does not light, replace the power supply.
If your power supply is running and nothing else is running, I would unhook all devices and leave just the CPU and video and memory in. If you get nothing, then the motherboard is probably bad.

replace the power supply of your cpu check if the blower fan is spinning during power on it means that your power supply is good if not replace the power supply with a new one

Click the following picture to enlarge:


CPU Overheated
If the system shutdown automatically after power on system for seconds, that means the CPU protection function has been activated. When the CPU is over heated, the motherboard will shutdown automatically to avoid a damage of the CPU, and the system may not power on again.

In this case, please double check:
1. The CPU cooler surface is placed evenly with the CPU surface.
2. CPU fan is rotated normally.
3. CPU fan speed is fulfilling with the CPU speed.

After confirmed, please follow steps below to relief the CPU protection function.
1. Remove the power cord from power supply for seconds.
2. Wait for seconds.
3. Plug in the power cord and boot up the system.

Or you can:
1. Clear the CMOS data.
2. Wait for seconds.
3. Power on the system again.

If after clearing the CMOS you still have no display, you may have damaged your motherboard, CPU, or RAM. If you need further assistance with this Motherboard, let me know.

I’m happy to help further over the phone at https://www.6ya.com/expert/jeremy_69f3cc28d95bf514

Open the case, and disconnect all the devices (CD, disk-drive, floppy-drive). Turn the computer on, and see if the fan on top of the CPU spins, if the fan in the power-supply spins, and (optionally) if a lamp on the motherboard lights-up.

If not, then you need to try a different power-supply.

Hi:
Since you swapped the power supply already, and have disconnected the DVD, CD, and floppy, that leaves the hard drive and motherboard!

Look the motherboard over, and see if there are any capacitors that are bulging or leaking out on the tops.
Is the inside of the computer very dusty? Check and make sure when you power up the tower, that the cpu fan is spinning up.

Your CPU could be overheating, so removing the Heatsink fan and re applying thermal paste is an option too
If it is, try resetting the CMOS on the motherboard, or pulling the CMOS battery for a minite.
Do you get anything to display on the screen?
If you have more than one stick of memory, take out one of the sticks if possibleif possible.

Disconnect the data-cable and power-cable from the extra hard-drive, and try again. If the problem is the same, then the extra hard-drive, by itself, is not the problem. Borrow a power-supply, and connect it to the motherboard, and see if the alternate power-supply solves the problem.