Over the past month I've been hitting excessive thermal heating on my laptop and kidle_inject has been kicking in to try and stop the CPU from overheating (melting!). A quick double-check with older kernels showed me that this issue was not thermal/performance regression caused by software - instead it was time to clean my laptop and renew the thermal paste.
After some quick research, I found that Artic MX-4 Thermal Compound provided an excellent thermal conductivity rating of 8.5W/mK so I ordered a 4g sample as well as a can of pressurized gas cleaner to clean out dust.
The X230 has an excellent hardware maintenance manual, and following the instructions I stripped the laptop right down so I could pop the heat pipe contacts off the CPU and GPU. I carefully cleaned off the old dry and cracked thermal paste and applied about 0.2g of MX-4 thermal compound to the CPU and GPU and re-seated the heat pipe. With the pressurized gas I cleaned out the fan and airways to maximize airflow over the heatpipe. The entire procedure took about an hour to complete and for once I didn't have any screws left over after re-assembly!
I normally take photos of the position of components during the strip down of a laptop for reference in case I cannot figure out exactly how parts are meant to fix on the re-assembly phase. In this case, the X230 maintenance manual is sufficiently detailed so I didn't take any photos this time.
I'm glad to report that my X230 is now no-longer overheating. Heat is being effectively pumped away from the CPU and GPU and one can feel the additional heat being pushed out of the laptop. Once again I can fully max out the CPU and GPU without passive thermal cooling mechanisms being kicked into action, so I've now got 100% of my CPU performance back again; as good as new!
Now and again I see laptop overheating bugs being filed in LaunchPad. While some are legitimate issues with broken software, I do wonder if the majority of issues with the older laptops is simply due to accumulation of dust and/or old and damaged thermal paste.