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What can be wrong with a motherboard that only works when I swap the CPU, turn the laptop on, then off,  and then put the original CPU back?

Posted on 2011-03-23
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Last Modified: 2012-05-11
Hello again experts. I need help with a Gateway M-7301e laptop and a very strange problem. It was working fine until one day pushed the ON button and didn´t gave any video signal, just all leds blinking like crazy. In fact I had to take out the battery in order to turn it off.

I suspected and tested some things to troubleshoot the problem, like the memory modules, the battery, the AC/DC adapter, with no success. So I looked around for an used CPU that could fit the MoBo and surprinsingly I found one Intel Core 2 Duo T5270 that made the laptop to work again (the original CPU is an Intel Dual Core Pentium T3200). So I thought the problem was the CPU, and to confirm it I swapped back the CPUs, but for my surprise again, the laptop worked ok. Turned the laptop off and on many times to see if the problem appeared again but it didn´t. The laptop worked just fine. So I decided to do some more testing and ran MemTest for about an hour, and then Prime95 for another two hours. None of them showed something bad. So I decided to turn the laptop off and let it stand for the night.

At the next day I tried to turn the laptop on and nothing but the blinking leds happened again. So I took out the original CPU and tried to turn the laptop on with no CPU on it, just for the heck of it. I put back the original CPU and still nothing, just the blinking leds. So I swapped again the CPUs and boom, it worked again (with the Core 2 Duo CPU). Once again put back the original CPU (the Pentium Dual Core) and the laptop kept working. Well, until it cooled down again.

Do you have any ideas of what can be wrong and how to fix it?

Thank you very much in advance.
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Question by:milnerflores
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Expert Comment

by:MaximumIQ
ID: 35203422
I had a similar issue with an Lenovo not too long ago and it turned out to be the BIOS was acting up. Don't ask me why the BIOS would make it act that way, because it still makes no sense to me. Even IBM support couldn't explain the problem but said their diag tools pointed to the BIOS. They changed the mobo and it was up and running like a champ again.
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Expert Comment

by:edbedb
ID: 35203531
Have you tried leaving the Intel Core 2 Duo installed to see if it boots after cooling down?
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by:nobus
ID: 35205166
could be something wrong with the cpu - i had almost the same happening; booted with one board, not in another, then not in the original...
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Expert Comment

by:asidu
ID: 35205229
Solving intermittent problems is a challenge and time consuming.
If you have the spares at hand you could change them and locate the problem.

When you say the lights are blinking...did the intial flash appear on power on?

Since you are able to boot back after changing the CPU, it could be of an issue of poor joint.
Ensure every thing is plugged back in securely.
I would suggest that you reinsert the CPU again and see if it boots again.
Also use a fresh layer of thermal by removing off the old thermal paste.



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Expert Comment

by:asidu
ID: 35205235
>>Also use a fresh layer of thermal by removing off the old thermal paste.<<
Above line to read as:

Also use a fresh layer of thermal paste by removing off the old thermal paste
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by:nobus
ID: 35205964
or try another cpu
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Author Comment

by:milnerflores
ID: 35217497
Thanks for your quick responses. I did some testing after reading your comments, and this is what happened.

After I submitted this question, the laptop was working with the original CPU and I was expecting the problem would arise again on the next power up since I let it rest over night, but it did not happened. The laptop worked as if never had failed. So I decided to update the BIOS inspired on MaximumIQ's comment to see if this could solve the problem (I know he said that in order to solve his problem they had to change the entire motherboard, but I decided to give it a try anyhow). As usual, the laptop kept working fine (rebooted it like four or five times) until I let it rest for about two hours. After that, the problem arose once more. So I did the CPU swapping in order to test what edbedb suggested, but this time the laptop didn't work. And now it gives the blinking leds all the time, no matter what CPU is installed (probably the BIOS update made the motherboard unable to use the Core 2 Duo CPU).

I'll keep on trying reinserting the CPU and swapping them to see if I find some pattern and I'll let you know. In the meantime if you come up with another suggestion it would be extremely appreciated.
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by:nobus
ID: 35221035
it looks like a bad capacitor on the mobo - no signs of bulging or leaking ones??
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Author Comment

by:milnerflores
ID: 35237728
Ok, this is what I've found so far.

After performing some weird (and pointless I may admit) experiments with my CPUs over the weekend, the laptop was still dead in the morning. So I read nobus' comment and decided to take a closer look to all motherboard's components to see if I could find something strange that I missed the first time. I did not find any leaking capacitors since the MoBo has only solid state capacitors, but I did find something strange with an IC near the miniPCI port. This IC (an ITE's IT8502E that turned out to be a super I/O controller chip) had like ten of its pins corroded by some sort of liquid spill. Fortunately the damage wasn't that bad, so I cleaned it up and tried to eliminate any short circuit between pins with a fine needle, which I beleive did it successfully, because after this procedure the laptop went up and running again.

Now, after reading the IT8502E's description here:

http://gmb.viatech.com/resource/jsp/PartnersSolutions/Partners/ITE/index.jsp

I believe (or hope, should I say) that definitely this was the problem. So I'm just waiting to see whether the problem arises again or not in a couple of test days to declare this question officially closed, and of course to award points.

I'll let you know how this turned out at the end.

Greetings.
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Expert Comment

by:nobus
ID: 35238650
good to see you found a problem; waiting for results
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Author Comment

by:milnerflores
ID: 35317397
Well, after another few days of testing the problem is still there, what makes me thing that the ITE's super I/O chip is damaged, and the only way to prove it is to replace it, but that is beyond my reach so I'll leave it that way. The good thing is that the laptop turns on like two thirds of the time, and when this happens it works fine so, I'll work this way until I find a not to expensive replacement motherboard.

If you don't have any other comments I'll close the question.

Thanks again.
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Accepted Solution

by:
nobus earned 500 total points
ID: 35321139
look on e-bay -  you can find the same model with a cracked screen..
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Author Comment

by:milnerflores
ID: 35325580
Thanks for your advise about eBay. I'll do that.
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