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CPU fan spins on and off repeatedly


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#1 sghamghamy

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Posted 08 May 2015 - 12:32 AM

I  am building my second desktop. After connecting a HDD, 8 gigbyte(2*4) Memory modules, PCIe Video card,CPU  stock fan  and adding Thermal compound to the top of CPU, I decided to test the CPU fan. Noticed there is power to cpu but the cpu fan spins on and off repeatedly. Before I do all these, I  tested the PSU without attaching it to the mobo and it was working fine.

 

Next I removed all the components except  the cpu and its fan, yet when I turn on the PSU, it spins on for like 20 seconds and halts for 5 seconds and again.  I know the cpu fan should be spinning continuesly. The fan is conected to CPUFan on the mobo. 

 

The mobo is outside of the case. Therefore non of the front panel cables are attached to the mobo.  I use a flat screwdriver to short out the power-on switch. Why is CPU not spining continuesly?.  Is it because there is an open circut somewhere on the mobo?.  Is it because the CPU fan get stock somehow?.

 

Any help is appreciated.

                   Shervin



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#2 jonuk76

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Posted 08 May 2015 - 11:28 AM

Is there any video output or POST beep?  What are the specifications of this PC?  Are all parts new?

 

Not quite the same but I had some similar symptoms when I had a power supply failure recently.  Computer would "turn on" but not POST, some cooling fans turned, others were struggling to spin and would maybe start for a few seconds and then stop.  The PSU had failed, and although there was some (low) output on the 12v lines, it was definitely blown. Replacing the PSU cured the problem entirely.  That is just an experience I had recently... Your issue could be something else entirely.


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#3 sghamghamy

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Posted 08 May 2015 - 12:02 PM

Hi,
All the parts are new. I tested the PSU Separetly and it works just fine.
The Parts are as follows:

Mobo: MSI H77MA-G43 mATX
PSU: mATX Form Factor FSP400-60GHS(85)-R 400 W
8 Gig (2x4) DDR3 Memory module
Intel Pentium 2.9 MHZ With Socket 1155
1 Gig PCIe Video Card. VGA, HDMI,and DVI ports.

I removed all the parts except the CPU and its stock fan, yet it was doing
the same thing- would spin for about 20 seconds then stop spining for about 5 seconds repeatedly unitl I turn off the switch on the PSU.
I did build the same system but with ATX mobo form factor and everything worked fine  about two
 years ago.
I am thinking there must be some setting in BIOS setup that controls the temprature of the CPU.
Or there must be an open circut somewhere on the mobo that makes cpu to stop spining for few seconds.

The mobo is not in the case.  It is layed out on my desks with some parts attached. I don't have the case yet.

So non of the front panel wirings are attached to the motherboard.
Any suggestions is welcomed.
Thanks
Sg
 


Edited by sghamghamy, 08 May 2015 - 12:06 PM.


#4 Kilroy

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Posted 08 May 2015 - 12:39 PM

How did  you test the PSU to make sure it was good?

 

Do you have all of the power connectors attached to the motherboard?  There looks to be a four pin connector behind the PS2 ports.  I don't remember what happens when you don't plug that power in, but it doesn't work.

 

Is the motherboard known good?



#5 sghamghamy

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Posted 08 May 2015 - 01:07 PM

Hi

The mobo is brand new. You test PSU itself by using a wire connecting one end to green color wire and the other end to any black color wire on the P1. Then turn the switch on the back of PSU on.  If the CPU Spins continuesly, it means it is working fine. 

 

P1(24 pin) is connected, cpu fan is connected to CPFAN on the mobo and 4pin cable (12V) for cpu is connected.

 

Sg


Edited by sghamghamy, 08 May 2015 - 01:08 PM.


#6 Kilroy

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Posted 08 May 2015 - 05:49 PM

Okay, so you didn't actually check the voltages coming from the PSU so the PSU could be defective.



#7 sghamghamy

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Posted 08 May 2015 - 05:54 PM

Thanks but I know it is not the PSU.  I will test voltage tonight when I go home.  I spoke with a MSI Tech support and he suggested me to check the CPU socket for any bent pin. That could be more likely the cause .






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