Heat pipe from a 15" MacBook Pro
How can you keep increasingly hot CPU and GPU chips cool while making laptops thinner?
The answer is smart cooling using a combination of heat-sinks, temperature sensors and airflow.
The Fujikura heat pipe is a good example of effective laptop cooling.
Here’s how it works:
1. The hottest components on the logic board are the CPU, GPU and Northbridge. The tops of the chips are connected via thermal grease to their contact plates (1.)
2. The heat is then carried (dissipated) via “pipes.” Inside these pipes are a spiral metal filling and fibers that “draws” the heat down the line.
3. On the pipe itself, temperature sensors (2) are placed to determine how hot the system is getting. More graphics intensive apps will produce more heat and the temperature sensor will report the temp back to the system to determine fan speed.
4. The heat is this taken to a heat-sink (3) which further spreads out the heat. A fan is connected to this heat-sink and draws the heat out of the system.
Pretty cool 
[ Fujikura ] [ Fujikura Technical Info ]
MacBook processor getting new thermal grease.
Thermal grease is a paste like substance that is used to aid a components heat transfer to a heat-sink.
In other works, thermal grease helps get the heat from a chip onto a heat-sink. The heat-sink then sends the heat to a fan or dissipates (spreads) it out.
Overheating can lead to component failure so making sure processor and graphics chips stay cool is very important. If thermal paste is not applied properly, chips can overheat and fail.
Here are a few good tips to keep in mind:
1. If you remove a heat-sink from a processor to perform a repair or upgrade, always clean the old thermal grease off (using rubbing alcohol) both the chip and the heat-sink and apply new thermal grease when re-assembling. This makes sure you have a fresh tight seal (no air pockets) and good conductivity.
2. Buy the good stuff. Different thermal greases have different heat transfer properties. Silver compounds transfer heat better and keep chips cooler than standard silicon. Cheap grease can also dry our faster and lead to higher temps. We use Arctic Silver 5.
3. Cover the surface of the chip (that makes contact to the heat-sink) but don’t apply too much. Too much thermal grease will keep the heat from getting where it needs to go (the heat-sink.) Spread the grease flat so they’ll be no air pockets.
4. Some of the higher end thermal grease contains metal which conducts electricity as well. Make sure that any excess grease is cleaned off of the logic board to avoid shorts.
FYI – Thermal grease is also commonly known as thermal paste & heat-sink compound.
MacBook Pro 15" with broken video.
The above MacBook Pro is showing broken or distorted video on boot. The cause is a failure of the video chipset (GPU) on the logic board. This is a good real world example of a failed NVIDIA chipset.
Some MacBook Pros (15″ and 17″) with NVIDIA GeForce 8600M GT GPUs that experience the above symptom (sometimes no video) may qualify for a free logic board replacement from Apple (up to 3 years from purchase.)
MyService, The Apple Store or any other AASP can perform a diagnostic to determine if the repair is covered. Contact us to learn more or select our free diagnostic service.
