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Fan starts up and then dies again repeatedly

Last response: in Systems
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March 23, 2012 12:17:26 PM

Hi,

I have a system that I have had for about 9 months. On 4 occasions (before mysteriously fixing itself) it has refused to boot.

Symptoms:

- All fans in the machine start up and then after about 8 seconds or so, the fans all shut down and restart. This occurs until I shut off the power (either by holding down on the power button or switching off the power to the PSU).

Things tried:

I have breadboarded the system so that only the PSU and the motherboard are connected together with no ram, expanision cards or anything else connected to the motherboard as suggested at http://www.tomshardware.co.uk/forum/261145-13-read-post... and it does the same thing. The PSU fan cycles as described before.

I have tried removing the bios battery with no difference.

I have tried a different PSU with no difference.

The cpu is passively cooled with a heatsink which I have currently left alone (due to the fact that it is obviously working as otherwise it wouldn't have mysteriously started working in the past).

Ideas:

Obviously this suggests that the motherboard is shorting somewhere though the fact that it randomly has started working again in the past suggests that nothing is burnt out on it. I would send the motherboard back to the people that built the machine but I am worried it will just start working again as it has in the past.....
a b V Motherboard
March 23, 2012 2:34:53 PM

You are probably on the right track... Either a short or you are going into protection mode on the motherboard.

If you have an anti-static bag large enough, take the MB out and put it on the bag for a few test runs. Maybe an intermittent short from mounting in the case. Could be as simple as arcing...

I assume you have tried this, but test with a single memory module and different slots. ...or different memory.

Hopefully you can keep plugging away and get it figured out. These types of issues are a PITA to say the least.
a b V Motherboard
March 23, 2012 3:19:03 PM

So the cpu has no fan? What cpu? Is it overheating and causing it to shut down?

March 23, 2012 3:35:45 PM

Hi all,

It's started working again.... Only thing that I can possibly think of is that there was one random cat hair on the bottom of the motherboard that I got rid off that might have been shorting it out. Either that or it just decided to randomly start working again to taunt me (as I had just asked and got an RMA number for the motherboard). Hopefully it will be happy from now on (it's a linux server so once I have it setup how I want it I shouldn't have to ever reboot....)
!