OT: Please explain how the heat sink and the thermal compounds applied "work"

Basically, I wanna know what the whole mechanic is behind it, how it works, etc. My brothers laptop, an HP, just shuts off, and viewing HWMonitor on it, it was his CPU (went up to 101C and then just DIED)

Its been having this issue for a while, but today we finally decided to open up the laptop, and here are 2 of a few pictures I took of the CPU and the heatsink: (BTW getting to the heatsink on this thing was ANNOYING! Also, orry fo the poor quality, iPhone pics)


Thats the CPU...you can see the thermal compound paste or whatever that was applied many years ago.


Theres the Heatsink with the same thermal compound.

Now, for me, this is the first time I see this stuff, feel it, etc, so I am no expert, and am in fact, highly ignorant on the matter....that said, the thermal compound is very clayish, kind of on the hard side...

Me and my brother are wondering, if we replaced the thermal compound with some Arctic Silver thermal compound, if maybe it will work better?

That said, once again I ask, how does a heatsink and the thermal compound "work"? How does it keep things cool, how does the thermal compound make a difference? What does the thermal compound do, whats its job?

Thanks a lot!

 

It probably will work better with the AS compound. Its job is to create a bond between the cpu and the heatsink. If you want to learn more look HERE.

 

Thermal compounds act as a layer to compensate for imperfections between the heatsink and CPU die (or sometimes an integrated heat spreader on certain CPUs). This is because the surfaces aren't truly 'flat' and do not match perfectly. In addition there are usually micro sized imperfections on the heatsink surface, CPU or both that the compound seals and provides a connection to form a close 100% contact bond and more efficient heat transfer.

If temps are shooting up to 101+ and then shutting off, I would start with cleaning everything out with compressed air.

The compound still looks relatively fresh and usable but as always from the factory, they go overboard. You actually only need a small amount to compensate for the imperfections. We'll go with the classic compressed and natural distribution system.

I would take a plastic surface (like a plastic butter knife or shim or even a small plastic spoon) and collect as much of the compound as possible that is on the heatsink and cpu and around the CPU for later use.

I would then clean the rest of the area and heatsink spotless with isopr. alcohol or similar.

Then I would take a SMALL dollop of the original compound, apply it to the center of the CPU and remount the Heatsink fan. Make sure the connection is secure and the heatsink is making firm contact with the CPU.

At this point, after re-assembly, turn on the unit and physically verify the CPU fan is working and moving warm air. Also make sure the laptop has enough breathing room. If the fan is broken and in the small, confined space, the unit will heat up and eventually shut off.

 

Thermal compound is used to eliminate all the air between CPU and heatsink, since air is a very bad heat conductor. So most of the heat CPU generates is being transferred to heatsink and spreaded out with fan. Better Thermal compond conductivity = cooler CPU = longer CPU lifetime = higher overclocks.

 

I'm also ignorant in this topic. This may help: I've seen the best solution for overheating is changing the cpu fan for a zalman's gpu fan.

 

I wouldn't recommend this, as the OP stated that the original compound is clayish/hard. Additionally, the compound is over four years old (as stated by the OP).

You hit the nail on the head with the rest of your post though

To the OP: use some Artic Silver 5 compound to replace the old compound. Also remember to only apply it to either the heatsink or the CPU (not both). Less is more in this case.

Duane

 

I would recommend Arctic Cooling MX-2 or OCZ freeze rather than AS5 due to better performance and non-capacitivity

 

The compound, by the pics, looks still wet and uniformly white in tone. It doesn't look dry or cracked. It could be the pics, but I was going by what I see, but I see where he mentioned its current status now. If the thermal compound is hard, then collecting it would be a moot point anyhow as it would be near impossible. Hopefully you have a packet of something on hand for a Q&D test.

I used to use AS5 for years, but I've switched to MX-2 too. No curing time, easier application and identical temps or even a degree or two cooler with the MX-2 and zero chance of any capacitive reaction (which is close to zero if you're careful anyhow).

 

Really? I use AS5 atm. I might try this MX-2 stuff next time I clean my computer.

Duane