Cooling for laptops

[Awesome14 0]

Over the last 10 years I've found laptops throttle the processor speed in order to keep fan noise down. I prefer the fan to run noisily, and the processor to run at full speed. I've developed tried and true mods for lappies and have demonstrated their effectiveness.

 

I have two Lenovo W541 laptop workstations with I7-4940MX processors and discrete nVidia graphics. On one I overhauled the cooling. Copper shim between CPU and hsf, AS5 on both sides. Shims between hsf and inductors near CPU and gpu, and shim on the gpu.

 

Used 'thinkpad_acpi' Linux kernel module to set fan to max speed. Ran mprime (prime95 for Linux) AND Unigine Heaven, alternating,  to cure the AS5. Then ran mprime. Temps were slightly high. But laptop processors tend to run hot. 

 

The I7-4940MX is a 3.1 GHz, 4.0GHz. Turbo processor. The modded machine ran at 3GHz. continuously running mprime, for weeks. The unmodded machine with the same max-fan-speed software tweak and stock thermal-interface material, throttled to 1.7GHz.  at the same running temps.

 

Clearly, laptop manufacturers are robbing performance off the top, by inferior cooling hardware and materials. Granted, getting the cooling mod to all fit together correctly with smooth, flat surfaces requires hours of work and materials not normally found sitting around the house.

 

I normally do not mod the CPU die. I abrade copper surfaces down to 1500 grit paper, and then polish with scapings from a bar of buffing compound. Everything is done on 1/2" plate glass to maintain flatness. The final mirror polish is done with the compound granules on a clean, damp cloth.

 

Desktop processors mostly have slightly raised corners, so smoothness is not as much of concern. You're going to get thermal-interface compond completely covering the center of the processor. The ideal is to fill the microscopic gaps between the cpu die and the hsf, but where there is metal on metal, have it be. 

 

Metal to metal provides 100s to 1,000s times the heat transfer of thermal paste. But, on a desktop, there are more effective cooling solutions than moving air. Most user are satisfied with their laptops, because the processor doesn't run full speed long enough to make a difference.

 

But I enjoy tweaking, and I do processor-intensive work, like batch editing 100s of large images, video rendering, security testing, password recovery, network testing; that are all severely compromised by poor, stock laptop cooling solutions.