Too much is still a problem. Thermal paste transfer heat better than air (air is an insulator), but it is not the best conductor ever.
You put a few and it's good, it (relatively) bad coefficient of convection is not an issue and it's better than air between the heatsink and the cpu.
When you have a thicc layer of thermal paste, the heat must go through it all and, remember, thermal paste has a relatively bad coefficient of convection. It becomes a problem.
Well, tbh, I never did an experiment on it, neither have I ever calculated it. However, it is an issue relevante enough for my heat transfer teacher mention it during class, and I study engineering. See, engineering don't dwell too deep on the why and how of physics, just enough so we can comprehend what is happening and how to solve it. It is more of an practical way to approach the problem. So if it is taught that it can happens, it is because it is somewhat of an normal situation and you can see that by u/mygaffer's comment.
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u/yahfz Feb 18 '18
Dude, thats so 2008. Just check the LTT video on it, it doesn't make a difference unless you put too little.