fan is accelerating too often

You should use a thermal monitoring program to actually see what the temperature of your system components are rather than just guessing. Your motherboard manufacturer may supply one, or you can use something like Open Hardware Monitor if you're running under Windows.

If your CPU is running too hot, odds are you didn't remount the heatsink securely enough or you put too much thermal paste - this last one is a common mistake among newer system builders. Arctic Silver 5 does have a break-in period but you should not notice enough of a temperature difference to cause this kind of behavior except possibly in extreme overclocking situations (I'd say at most 5°C)