# Can a heatsink really go bad?



## Maverickz (Jul 1, 2011)

I am working on an HP nc6400 that has an overheating problem. Originally the fan was not blowing so I figured that was the culprit. Once I pulled the fan out I realized that a fairly large dust clump was preventing the fan from spinning. So I cleaned up the fan and used a dry toothbrush to clean out the fins on the heatsink. I reinstalled the fan (I did NOT remove the heatsink) and booted up. 

The fan of course was now spinning and cool air was coming out where it should. I left the unit running for a while and noticed (using a couple of different temp monitors) that it was still a bit on the high side (~70C), so I decided to see what would happen if the processor was taxed at all. I loaded up a tv network website and started playing a full episode video and within seconds the CPU temp shot up to 100C and the laptop turned off. I did notice that the fan speed increased but not until around 90ish C. Unfortunately there is no fan monitoring or control settings in the BIOS and Speedfan and other tools don't even see the fan so they can't control it either.

The weird thing is the copper portion of the heatsink where the fins are and the fan blows through was fairly cool to touch, the copper potion of the heatsink above the CPU was decently hot but did not feel near 100C. The really hot part was the gray metal that sits under the copper bar but on top of the CPU. Even the 4 screws that hold the heatsink down were extremely hot. So to me it seems that the gray metal is pulling heat out of the processor but not transferring it to the copper bar of the heatsink. If this is the case I can't imagine putting new thermal paste under it would help as it seems the problem is between the gray part and the copper part. 

So this leads me to my question, can a heatsink really go bad? Was this one just maybe defective from the factory or is this just a really craptastic design and replacing it will be pointless? For reference, below is a picture of the heatsink in question. The fins that the fan blows through are at the bottom of the picture.

Thanks for any answers.


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## dai (Jul 2, 2004)

you have to renew the paste on the cpu anytime you disturb the h/sink

Arctic Silver Incorporated - Route to Product Instructions for Arctic Silver 5


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## Maverickz (Jul 1, 2011)

Unfortunately I am out of paste, which is why I didn't remove the h/sink. I guess I can go buy more and try it. It just seemed like the transfer of heat between the cpu and the gray metal was more than adequate but the transfer between the gray metal and the copper bar was where the failure was. Unfortunately these two pieces are welded together so I can't use paste between them.


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## dai (Jul 2, 2004)

do the paste and see where you stand


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## Maverickz (Jul 1, 2011)

OK I reset the h/sink with fresh thermal paste, let it idle >20 hours. Still overheats within minutes of doing something processor intensive such as watching video. I went ahead and replaced the fan now as well and that seems to have slightly increased the time to overheat by a couple of minutes but not by a lot.

By the way my local supply house house was out of Arctic Silver 5 so I had to go with Arctic Silver Ceramique, which I know isn't quite as good but should be adequate for this application and is more than likely MUCH better than the original factory thermal compound.


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## dai (Jul 2, 2004)

did you follow the instructions for applying the paste

Arctic Silver Incorporated - Route to Product Instructions for Arctic Silver 5


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## Maverickz (Jul 1, 2011)

Yes I did.


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## oscer1 (Jan 27, 2010)

is the the copper tube making good contact with the heat sink? do you see any air in between them?


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## GZ (Jan 31, 2010)

It is rare, but the heat-pipe can fail. (the copper tube between the contact plate and the heatsink). 

The heat-pipe contains a liquid that vaporizes and condenses between the hot and cold ends which causes the transfer of heat from one end to the other. If there is a crack or opening in the heatpipe, this liquid can dissipate leaving the heatpipe near useless.

Unfortunately, I know no way of testing the heat-pipe for proper function, but if the contact plate remains hot whilst the heatsink fins stay cool, it is likely the pipe may have failed.


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## oscer1 (Jan 27, 2010)

Thanks gavinzach for reminding me of that, i have read that some where before.


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## Maverickz (Jul 1, 2011)

Ok it sounds like I may indeed need a new h/sink. I wonder now if I should consider a used h/sink from eBay. They all claim to be tested, but the question is if they are tested under a load to see if they REALLY work, or if they work just enough to keep it from overheating while idling.

Just for grins I did (fleetingly) consider melting a penny to try and fill in any gaps that might exist between the pipe and the plate but that would probably be harder than buying a new h/sink anyway.


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## GZ (Jan 31, 2010)

Maverickz said:


> Ok it sounds like I may indeed need a new h/sink. I wonder now if I should consider a used h/sink from eBay. They all claim to be tested, but the question is if they are tested under a load to see if they REALLY work, or if they work just enough to keep it from overheating while idling.
> 
> Just for grins I did (fleetingly) consider melting a penny to try and fill in any gaps that might exist between the pipe and the plate but that would probably be harder than buying a new h/sink anyway.


You would likely cause more issues than not by doing that... Purchasing a used heatsink from eBay would be prudent as long as the seller is offering some kind of guarantee.


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## Maverickz (Jul 1, 2011)

Ok with the new h/sink it will now play videos without cutting off but it is still running a bit hot for my taste. It is staying in the high 80's and low 90's with an Intel processor. The thermal paste was applied properly but has not had time for the full break in period yet.


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## GZ (Jan 31, 2010)

How are your temperatures now?

Sorry it's been a while, but I have been busy the last few months and lost track of a few threads. Unfortunately this was one of them.


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