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CPU fan turns on and off, wont boot

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July 13, 2007 6:11:46 AM

Hi everyone,

I have an issue i cant resolve myself.

I've built a core duo 2 based PC recently but when i turn it on, the CPU and PSU fans would turn on for a second, then switch back off. This will repeat until i unplug the power. I thought the issue was the power supply so i tried using another one but the same problem reoccurred.

I tried removing all other hardware just having the cpu, motherboard and power supply connected, and it did not make those diagnostic beeps you would hear when the ram isnt installed.

Does anyone have any ideas ?

Here are the specs.

Core 2 duo E4400
Asus P5K motherboard
1 gig Kingston 667 ram
gigabyte 8600GT
Antec Earth Watts 500W PSU

Thanks in advance!

July 13, 2007 6:40:25 AM

First try CMOS reset according to the manual, then try assembling mobo, ps, ram graphics and HD outside of the case on the stat bag or other non static surface. Could be a short, although usually the PS won't restart unless power is removed. It's worth a try.
July 13, 2007 6:49:06 AM

That problem sounds like PSU or BIOS. I would remove the motherboard from the case. Place the motherboard on the box it came in. Install 1 stick of RAM (in the correct slot). Install the video card. Hook up the Power Supply. 24 pin to motherboard. 4 pin to motherboard. 6 pin to graphics card. Hook up the monitor to the graphics card then power it up by shorting the two pins briefly that are normally connected to the power button (the two pins are marked power and you may need to refer to the motherboard manual to properly identify them).

If it still won't power up. Unplug the power cord to the power supply then remove the coin-sized BIOS battery and wait a few minutes to let the whole thing discharge. Sometimes you have to follow the motherboard procedure for resetting the BIOS (removing the battery doesn't always work) by moving a jumper but in my experience I have only had to do that a few times.

I have brought many systems back from the dead with this procedure. If you can get it to POST, then you can put it all back in the case and try again. If it still boots, then start adding stuff back in one device at a time.

Be carefull with static discharge the whole time. Repost on your progress and I will leave the thread open overnight and check back to see how you made out
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July 13, 2007 9:46:36 AM

Thanks for the suggestions guys. I'll do that once i have some free time.
July 15, 2007 3:56:34 AM

I got it working! Turns out to be a short somewhere. Thanks again for all your help guys.
July 15, 2007 5:58:50 AM

Great! See ya' around. =)
July 29, 2007 7:13:55 AM

Hell folks,

I have the same issue. Same motherboard.
I'm writing with the computer causing me this problems, so when it finally boots it works well.

My problem is that this on and off fan thing reappear every day.
I upgraded the BIOS, but it did not change anything.

The last test I've made is erasing the BIOS by removing the batteriy and doing the jumper think. This operation is not sucessful until I unplug My PSU.

What you think about this ?
Should I send my MB RMA ?

Thanks

Tim
July 30, 2007 8:20:42 AM

Hi again,

Some more details and hints:
I usually power off my whole computer through a power switch where all my PC and peripherals are plugged.
I noticed that if I leave this switch on, the fan on/off thing is not occuring. But when I shut all off, I have to reset again my BIOS.

If I shut all off for a short moment, like 1-2 mn. I can power on my PC without a problem.

Conclustion
The problem do not appear when the MB is still powered.
And I don't like that !

Tim
July 8, 2011 7:41:15 AM

Help! I know this is 4 years too late, i have to same problem, fan turns on for half a second if not, less then turns off. If i hit the turn off and on the psu then it allows me to repeat, but only when i do that, i tried clrcmos but that changed nothing, being off for 10 mins does nothing.

If there is a short.. how do i find it?

Ive juts removed the battery still waiting to try that.
July 8, 2011 7:52:53 AM

Ok so my system still doesnt boot.
If i removed the 8pin connector for the PSU, then the motherboard will power and run (or at least as far as much as it can without the connector) and tried 2 different PSU's, any idea?
August 22, 2012 7:40:22 AM

kshipper said:
That problem sounds like PSU or BIOS. I would remove the motherboard from the case. Place the motherboard on the box it came in. Install 1 stick of RAM (in the correct slot). Install the video card. Hook up the Power Supply. 24 pin to motherboard. 4 pin to motherboard. 6 pin to graphics card. Hook up the monitor to the graphics card then power it up by shorting the two pins briefly that are normally connected to the power button (the two pins are marked power and you may need to refer to the motherboard manual to properly identify them).

If it still won't power up. Unplug the power cord to the power supply then remove the coin-sized BIOS battery and wait a few minutes to let the whole thing discharge. Sometimes you have to follow the motherboard procedure for resetting the BIOS (removing the battery doesn't always work) by moving a jumper but in my experience I have only had to do that a few times.

I have brought many systems back from the dead with this procedure. If you can get it to POST, then you can put it all back in the case and try again. If it still boots, then start adding stuff back in one device at a time.

Be carefull with static discharge the whole time. Repost on your progress and I will leave the thread open overnight and check back to see how you made out


Hi Kshipper, one word: yourawesome
:) 
August 23, 2013 3:54:17 AM

HELLO GUYS I HAVE 100% GURANTED SOLUTION FOR THIS FUCKIN PROBLEM
IT HAPPENED TO ME YESTERDAY I TRIED EVERYTHING NOTHIGN WORKED FOR ME THEN I WOKE UP TODAY AT 4 AM AND I START TO SOLVE MY PC ISSUE AND I FIXED IT ALL U HAVE TO DO IS TAKE OUT UR PROCESSOR AND THE HEAT SINK USE A TISSUE PAPER AND AN ALCOHOL OR PETROL RUB THE TISSUE PAPER WITH IT 1ST CLEAN THE HEAT SINK LET IT DRY AND THEN 2ND CLEAN THE PROCESSOR SILVER METAL SIDE REMOVE ALL THE THERMAL PASTE ON IT WHEN U CLEAN IT VERY NICELY THEN PUT IT BACK IN THE SOCKET AND USE ONE INCH OF THERMAL COMPOUND ON THAT SILVER PROCESSOR METAL AND THEN TIGHTLY CLOSE THE HEATSINK AND UR FANS WILL START WORKING LIKE BEFORE IF UR PC WONT SHOW DISPLAY TRY TO CHECK 1 RAM IN ALL SLOTS AND THEN UR DONE AND UR PROBLEM WILL BE SOLVED IA M SO HAPPY I FIXED MY FUCKIN PC I THOUGHT MY MOTHERBOARD IS GONE NOTHING IS IMPOSIBLE TRY TRY AGIN AND ATLAST U WILL BE SUCCESFUL HOPE N SURE IT HELPED U
December 31, 2013 9:05:24 AM

As kshipper said:
"If it still won't power up. Unplug the power cord to the power supply then remove the coin-sized BIOS battery and wait a few minutes to let the whole thing discharge. Sometimes you have to follow the motherboard procedure for resetting the BIOS (removing the battery doesn't always work) by moving a jumper but in my experience I have only had to do that a few times."

This is what worked for me and not Billie Jean's 100% gurantee.
January 6, 2014 12:15:59 AM

oh really i tried evrything whatever i could i did battery removing and many more stuff nothing worked i told in post which i did and my pc is still working perfect
!