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Computer not booting - CPU fan not spinning

Posted on 2011-10-07
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Last Modified: 2012-05-12
Hi,

I'm working on a custom tower for a client that is not booting up. Here are the symptoms:

1) The screen doesn't come on at all
2) When the power button is first pressed, the CPU fan jerks a little but doesn't start spinning
3) The other fans in the case are spinning fine.
4) I removed the graphics card and memory but am not hearing the beeps I should be for missing RAM.
5) I also tried a different power supply with the same results.

Does anyone have an idea what the problem is?
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Question by:TrekSoft
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36 Comments
 
LVL 11

Expert Comment

by:David Kroll
ID: 36932632
Try reseating the CPU and check that the pins in the CPU socket all look straight.
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Expert Comment

by:jhyiesla
ID: 36932674
I'd start with replacing the CPU fan. Unless it's some weird cooler, putting a new muffin fan in should be an inexpensive and simple thing. Then at least you know that the CPU has adequate cooling. If it still doesn't go, I'd do what the other expert says and check the CPU for proper seating AND remove the heat sink and replace with fresh thermal paste.
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LVL 16

Expert Comment

by:sjklein42
ID: 36932880
CPU fan would not prevent BOIS screen from appearing.

Are you sure the second power supply you tried was good?  It really sounds like a power issue.

Also check the motherboard for bad capacitors.  See http://en.wikipedia.org/wiki/Capacitor_plague
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Assisted Solution

by:lrpage
lrpage earned 668 total points
ID: 36932910
or the bad fan allowed the cpu to over heat and die.  Thus needing to replace the cpu
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Expert Comment

by:web_tracker
ID: 36932927
Since you tried a known good powersupply, I would definitely try changing the cpu fan or check to see if anything is obstructing the cpu fan such as dust, cabling, etc. Does the fan move freely when you turn off the computer and spin the fan with your finger? If it is clean and spins freely check the connection of the fan wire to the mobo to see if it is firmly seated. If these things checkout replace the fan. Then check the cpu. If everything checks out and you have already replaced the fan the problem could be a bad mobo or a cpu.
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Author Comment

by:TrekSoft
ID: 36932978
I tried reseating the CPU and that didn't resolve the problem.

Also, what sjklein42 makes sense - if it was just a problem with the fan, I think I would be getting error beeps when I removed the memory and a message on the screen.

And yes, I'm sure the other power supply is good.

I think Irpage might be right - the computer was working fine until they moved it physically to another location and then it had that problem. And when I was working on it, I did see a thick wire blocking the fan but I wasn't sure whether that was something I'd moved into place or whether it was already there.

If it was there to begin with, I think it would have easily blocked the fan from running and perhaps damaged both it and the cpu as a result. I guess won't know though for about a week until I get a new CPU if that's what the customer decides.
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Author Comment

by:TrekSoft
ID: 36933098
Hmm - I happened to have an extra Intel Cor 2 Duo processor which the motherboard supports and is the same socket type (but I'm not sure if the FSB matches) and still have the same problem. Could it just be that it's because of an FSB incompatibility or does this show it's something else?
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Expert Comment

by:web_tracker
ID: 36933561
The cpu fan still does not spin up after inserting the other cpu? It could be a bad mobo, if a known good cpu and a fan replacement does not solve this issue. You did make sure the CPU fan was properly plugged in right?
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Author Comment

by:TrekSoft
ID: 36933563
Yes I did.
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Expert Comment

by:web_tracker
ID: 36933635
I would remove any pci cards, just leave the video card Plugged into the slot if the board does not have an on board video card. Remove any sata or IDE cables from the mobo, disconnet any case fans that are plugged into the mobo, disconnect any front usb cables that plug into the board. Leave only the cpu fan plugged into the mobo. Plug only one stick of memory into the board. Unplug any cabling at the back of the computer except for the power cord, video cable, keyboard and the mouse. Then try to power on the system. If it posts then some thing that you unplugged is shorting out the system. You can try plugging in items one at a time to see which item is causing the problem. If after disconnecting all these items you pretty well narrowed out the problem of a bad board. As the following did not solve the issue:
Known good cpu
Known good powersuppy
reseating the memory
fan appears to be working
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by:sjklein42
ID: 36933770
Did all the capacitors look ok?  That's #1 cause of a bad motherboard.
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Author Comment

by:TrekSoft
ID: 36933843
Yes they did. However, given that replacing the processor didn't work, I chose to go ahead and replace the motherboard. I'll see if that works.
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by:nobus
ID: 36935355
here is how i handle this problem : i use the minimum setup, as described in my article  
http://www.experts-exchange.com/Hardware/Components/Motherboards/A_1945.html      (Short-overview-of-how-to-troubleshoot-bad-hardware-when-a-pc-does-not-post)
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by:dejaanbu
ID: 36935685
Try to test the CPU and CPU Fan with other PC. if both is working fine, then you don't waste your time. Simply change motherboard or give for repair. I Hope it will help you and save your time
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Author Comment

by:TrekSoft
ID: 36973753
So I just replaced the motherboard and still have the same problem - the CPU fan just jerks a little when the computer is turned on, the power and case fans turn on, and no beeps are heard.

Does this indicate it is the CPU or the fan or both?
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Accepted Solution

by:
_ earned 668 total points
ID: 36973844
hmmmm... does the new mobo boot with the spare cpu?

If yes, then it sounds like the old mobo AND cpu got cooked (rare, but happens).

If no, then either the new mobo is DOA, or the old mobo and cpu are killing the new ones as they are tried (even rarer, but happens).
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Author Comment

by:TrekSoft
ID: 36974158
I don't have the spare cpu with me now so I'm planning to just order a new processor and fan.
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by:web_tracker
ID: 36974564
I would buy a new power supply... You said you replaced the powersupply but was the powersupply new or just used? Was the power supply the same wattage or higher?
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Expert Comment

by:nobus
ID: 36975174
the other fans (case fans, power supply fan all use 12V from the PS 12V rail
the cpu does use that also, but is speed controlled
did you replace the fan yet, or test it on another motherboard? with known working cpu ?
i would try that before buying a new cpu
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Author Comment

by:TrekSoft
ID: 36976891
Hi Nobus,

But wouldn't I get some beeps if it was just the fan?
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by:nobus
ID: 36977985
maybe - it depends on what is bad - it can be the sensor also (still reporting ok status)
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Author Comment

by:TrekSoft
ID: 37010923
Today I installed the new CPU and fan and found that while the new fan works fine (both in the new motherboard with the new CPU as well as the old motherboard with the old CPU) the brand new motherboard with the used-working CPU which just arrived doesn't work.

So this is now the full history:

Computer arrives not booting up (or giving error codes when memory is removed) and with the fan not working.

I took a known working CPU and put it in the motherboard with no change in outcome (since the fan wasn't spinning I'd turn it off quickly so it wouldn't overheat).

I then took that known working CPU and put it in a known working motherboard and now they don't boot up either.

I purchased a new motherboard, put the old CPU and fan in it and experienced the same problem (since the fan wasn't running I would quickly turn it off).

I purchased a used-working CPU and fan and while the fan works in both old and new configurations, the new motherboard and new cpu don't boot or give error codes with memory removed.

Could it be that the original problem was caused by the fan failure and that now it's a chain reaction of the motherboard damaging CPUs and then the CPUs damaging new motherboards?
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Author Comment

by:TrekSoft
ID: 37010944
Also, I don't know if this is relevant or when it happened but I noticed that on the contacts of the CPU carriage of the old motherboard, there was a little dust and also on the bottom of the old CPU, there was a tiny bit of what I believe was thermal grease.
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Assisted Solution

by:nobus
nobus earned 664 total points
ID: 37011212
>>  I then took that known working CPU and put it in a known working motherboard and now they don't boot up either.   <<   looks like that cpu was killed byt he mobo --so yes, chain reaction
you can clean thermal grease with isopropyl alcohol  - it should not touch pins
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Author Comment

by:TrekSoft
ID: 37011216
So I should get a new motherboard and cpu?
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LVL 93

Expert Comment

by:nobus
ID: 37011267
that looks like it is the only way out
i assume the motherboards were the same model ? if not, you may have been shorting it to a mounting standoff
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Author Comment

by:TrekSoft
ID: 37011279
They were not the same model but the processor was supposed to be compatible according to the specifications.
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LVL 93

Expert Comment

by:nobus
ID: 37011477
did you verify the standoffs were the same?
if not, i would test both boards OUTSIDE the pc, on a wooden board
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Author Comment

by:TrekSoft
ID: 37011580
Actually, the first time I tried the new keyboard it was outside the case on I think the top of the glossy cardboard box it came in. Would that have caused a problem?
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Author Comment

by:TrekSoft
ID: 37011585
Oops, I mean motherboard not keyboard.
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LVL 93

Expert Comment

by:nobus
ID: 37011589
no, only if it were conductive
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Author Comment

by:TrekSoft
ID: 37011615
OK, well thank you for your help. I'll split the points up.
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Author Comment

by:TrekSoft
ID: 37011616
OK, well thank you for your help. I'll split the points up.
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LVL 32

Expert Comment

by:_
ID: 37012478
I second nobus, looks like you are now a member of the "chain-reaction club".
Welcome aboard.   : |

I haven't had any problems using the glossy side of the box, but it makes me nervous. But I try to avoid it, just to be sure.
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Author Closing Comment

by:TrekSoft
ID: 37050241
Thank you all for your help - I feel much better about concluding it's a chain reaction with your backup on it.
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by:_
ID: 37051368
Thank you much.    : )
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