I bought i5 8400. I'll be using it with stock cooler. I want to know if I'll see improvement in temperatures when I replace stock thermal paste with something better. THX
Pairing high end thermal paste with the stock cooler won't net you enough difference in temperature to make it worth your while. There is the possibility that the stock heat sink assembly will mitigate most of the gains you might otherwise see. If you're spending extra money on an aftermarket fan and heat sink assembly that has the capacity to deal with the extra heat transfer, then you might see practical gains from better paste, otherwise you're throwing money at the wrong problem.