The top of a Processor's case, and the bottom of a Heatsink are not perfectly smooth. A microscopic view would reveal, 'Hills, Valleys, and Pits'.
These imperfections create a void when the two surfaces meet, and Air pockets are created.
Air is an Insulator, Not a Conductor.
Thermal Paste is a Conductor. It helps to conduct heat from the top of the Processor, to the bottom of the Heatsink. It also fills those voids.
[ Typical construction of a Heatsink, is a plate of metal with tall, thin fins protruding from it.
The plate of metal is placed against whatever object needs to have heat transferred away,
(Processor in this case), and the tall, thin fins absorb the heat from the plate.
The tall, thin fins then radiate the heat away.
If a fan is used along with the Heatsink, the air flow helps carry heat away from the fins ]
The Satellite P100 series of laptops, (Includes the P105-s6104), have to be disassembled down to the motherboard, in order to access the cooling assembly.
In the Satellite P100 series of laptops, the Heatsink is usually attached to a Cooling Tube. The Cooling Tube attached to flat plates that sit on top of the Processor, and on top of the VGA chipset.
The Cooling Fan sits on top of the Heatsink.
Toshiba Satellite P105 Disassembly Guide,
This is Page 1. The pages can be accessed by clicking on Page 1 :: Page2 :: Page 3 :: Find another model,
at the bottom of the page.
Click on the photos in Step 17, 18, and 19, (One at a time), to view the Cooling Assembly I'm referring to.
Observe the photo in Step 19. Enlarge it.
See the curved copper Cooling Tube, and the brass heatsink plate it attaches to?
There is a number 3, and 2 on the plate.
To the right of the number 2 is the Processor.
The Satellite P105-s6104 uses an Intel Core2 Duo T5200 processor.
1.6GHz maximum frequency rate
2MB of L2 cache
Uses a Socket M processor socket)
This is a close-up view,http://www.cpu-world.com/CPUs/Core_2/Intel-Core%202%20Duo%20Mobile%20T5200%20LF80537GE0252M.html
In the heading where it states Specifications - Pictures (2) - Benchmarks - CPU ID (2) - Comments (0),
click on Pictures (2)
Now click on the photo under the heading Top View.
The square outside greenish part is a Circuit Board. (PCB or Printed Circuit Board) The dark rectangle in the center is the actual Processor. The Processor chipset. The circuit board has connections from the Processor chipset to the connecting pin on the bottom.
The dark rectangular shape is what is cleaned off, and fresh new thermal paste is applied.
I use Isopropyl Alcohol, (Rubbing alcohol), and Q-tips to clean. 91 percent alcohol is best.
[CAUTION!! Isopropyl Alcohol is EXTREMELY FLAMMABLE! Use in a well ventilated area, with NO sparks, or flames present! }
Apply a small pea sized drop of thermal paste on the center of the Processor chipset. Then the Cooling Assembly is reinstalled.
In the photo in Step 19, the VGA chipset is below the Processor.
It should also be cleaned, and new fresh thermal paste applied.
(Average cost of thermal paste is around $6)
The VGA chipset's circuit board is soldered to the motherboard. It isn't removable like the Processor.
Overheating may cause the solder joints to loosen enough, that the circuit board connections, (BGA), may come loose. This causes the VGA chipset to slightly lift up out of the motherboard connections. This can cause graphics problems. A special method is used to remelt the solder connections of the BGA, and the circuit board is put back in place. (Reflow)
Hopefully cleaning, and applying fresh new thermal paste to the Processor, and VGA chipset will solve your problem. Reflowing is usually done by the factory, although there are repair shops with the expertise, and correct machines. (Ka-Ching!) Most computer repair shops do not have the correct machines, nor the expertise.
All power removed from the laptop. AC adapter (Charger), and Battery.
Use an ESD wrist strap, connect the alligator clip to a good ground source. (Average cost is $3 to $8)
Use a multi-compartment container for the various screws you will remove, label the compartments for where the screws came out of.
There may be as a many as 60 screws, and 12 different types. Do NOT mix them up.
(You can use a clean egg container in a pinch. Label each egg holder)