Improving ThinkPad T420s Thermal Performance

NOTE: Some of this will apply to other ThinkPad's

The Problem

I bought a ThinkPad T420s, before this I used a ThinkPad X200 and I was used to the super cool (18C idle 35C under load) temperatures that the laptop had with the T420s however the temperatures where absurd (60C idle +100C under load), this clearly needs urgent attention.

The Solution(s)

Replace the thermal paste on the CPU & clean the fans

For any over heating computer, replacing the CPU thermal paste and cleaning the fans should be the first point of action. For me, I finished the lengthy process of replacing the thermal paste and fan cleaning on the T420s, and barley noticed any improvements in thermal performance. It was still worth doing though and should most certainly be done first.

For the disassembly, I recommend that you watch a video on how it should be performed, for the T420s specifically I used this video to disassemble the laptop, searching for your own specific model will show some useful results.

Using intergrated graphics

The T420s specifically (and some other ThinkPad models), come with two GPU's, in my case it's the NVIDIA NVS 4200M and Intel intergrated HD graphics. Using the NVIDIA GPU significantly worsens thermal perfomance, with the CPU sitting at 60C at idle. Switching to the intergrated graphics improves the thermal performance significantly with the CPU temperature sitting at around 45C at idle.

To actually switch between the GPU's, enter the BIOS settings and go into the "config" menu , then go to the "display" menu and from there switch to using the intergrated graphics.