Is it possible for a heatsink to stop sinking heat??

schwags

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I have a Toshiba satellite laptop in the shop right now with some odd symptoms. It is running very hot (85C) on idle. I have taken it apart, cleaned it (it was already very clean), put on new heatsink paste, reassembled and turned it on. Coretemp and HWmonitor both say it is running ~85C at idle! The fan IS running as I can feel air coming out of the vent, and it is barely warm. The bottom is a little warm, but not horribly hot. I understand how phase change heatsinks work, and I really don't think they can stop functioning since the operation is a simple effect of physics, but does anyone have another idea? Maybe the temp sensor in the CPU is bad? I haven't seen that before either.
 
Just because a fan is spinning, doesn't mean its good.. Is it running at full speed??

To my knowledge a piece of metal can't go bad.
 
If your not feeling very hot air coming out then I would think that would point to either a bad temp sensor OR the software that you are using to read the temp is not reading correctly.

And no, heatsinks don't go bad.
 
Silly question, so no offense,
but did you also check in the hidden area between the fins and the fan where build up can occur?
 
Yeah, I was pretty sure the heatsink couldn't go bad. I mean, It's not just a solid chunk of metal, it is a tube with a phase change liquid inside. But it is still sealed and nothing should be able to break that seal that I am aware of. The fan is running pretty quickly, so I think the only thing that makes sense is a bad thermal sensor on the CPU. I have tested with both coretemp and hwmonitor, two pieces of software that have been very good to me in the past. I'll swap in a spare CPU and see if that makes a difference.
 
No it is not possible.

The fan can stop working though... and the heat-sink can be broken loose, popped up or otherwise not fully attached... it can become full of dirt & debris, too.

IF it is properly attached, and the original Thermal Heatsink Compound seal isn't broken, and it is clean (not plugged with dirt), and the fan is spinning freely and powerfully, then it is working.

If the CPU is reporting too high a temp it is most likely a bad thermister on the motherboard not properly detecting the temp. I would try to first re-seat the same (cleaned) heat sink with Arctic Silver 5. If that fails to remedy the problem, try the same processor and heatsink on another motherboard.
 
Now for the real question:

How much heat would a heatsink sink,
If a heatsink could sink heat
 
Yeah, I was pretty sure the heatsink couldn't go bad. I mean, It's not just a solid chunk of metal, it is a tube with a phase change liquid inside. But it is still sealed and nothing should be able to break that seal that I am aware of.

Hmmm... look for cracks in the joints. Aren't heatpipes pressurised when hot?
 
Now for the real question:

How much heat would a heatsink sink,
If a heatsink could sink heat

LOL...alright there woodchuck!

I'd check the fan assuming it's not a passive heat sink.
Also check airflow in the case..although doubt that.
Have seen mobo temp sensors go bad.......sometimes a BIOS update can fix a known issue with that.
 
I think it IS possible for laptop heat-pipes to stop working properly.

I've seen it happen. You can tell because what happens is that the part near the chip gets hot quickly but the radiator end doesn't. It's not all that uncommon. I've diagnosed it, replaced the part and all works well afterwards.
 
I think Mobile Techie has the right idea here. I ordered a new CPU thinking it was the thermistor, but the new CPU made no difference. I disassembled AGAIN, this time running the board and heatsink/fan combo out of the shell. After a minute the spot on the heat pipe directly above the CPU was very hot, but only 1/2 inch away on the heatpipe it was room temperature! I guess the heat pipe really did stop transmitting heat. I will order a new heat pipe, install and report back.
 
Just thought I would report back. The heatsink (heat pipe more accurately) was the issue. The old heatsink must have lost its charge or something because the new heatsink keeps the temp down perfectly well. Go figure.
 
I think it IS possible for laptop heat-pipes to stop working properly.

I've seen it happen. You can tell because what happens is that the part near the chip gets hot quickly but the radiator end doesn't. It's not all that uncommon. I've diagnosed it, replaced the part and all works well afterwards.

You are correct sir. I had a liquid heat pipe in a Toshiba laptop fail not to long ago, end with processor hot as H*ll other end with fan (not spinning) cold, not cycling the liquid = bad heatsink, I've also seen a basic heatsink for a desktop warp and not make good contact to the CPU causing it to overheat.

remember as soon as you say its not possible...
 
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loll

lol @ "stop sinking heat" hahahaha

To answer your question. Sure if your using extremely old paste im talking 5+ years. Or maybe if your fan spins dangerously low, which could be caused by a bad thermal\environment sensor. Or since metal expands when heated, the pipes can expand loose.
 
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I think Mobile Techie has the right idea here. I ordered a new CPU thinking it was the thermistor, but the new CPU made no difference. I disassembled AGAIN, this time running the board and heatsink/fan combo out of the shell. After a minute the spot on the heat pipe directly above the CPU was very hot, but only 1/2 inch away on the heatpipe it was room temperature! I guess the heat pipe really did stop transmitting heat. I will order a new heat pipe, install and report back.

So basically what your saying is that.... the heat sink wasn't sinking any more heat? :D

"Titanic(r) Liquid Cooling Systems"
The unsinkable heat sinks.
 
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