[SOLVED] Crackling sound from H115i cpu cooler 10-30 mins after i start a game?

Dec 19, 2020
Hi everyone! Hope you’ve had a good day!

So, basically my problem is that every time I start to play games in about 10-30 mins the cpu cooler (H115i) makes a weird crackling noice. This happens once or twice and then it’s normal again. Before it could happen some hours in to a gaming session but when I increased the pump speed it only happens once or twice.

here’s a clip with the sound (sorry for the graphic card fan but I had to film the fan to rule it out; and it happens to be the best video containing the sound:
View: https://youtu.be/yoPhudzK4Eg

I’ve read that it could be bubbles, so I’ve tried to tilt the case in various directions but no luck so far. Do you guys think it’s airbubbles in the cooler that makes a sound like that? I’m 99% sure that it comes from the cpu cooler but it makes no sense to me that it happens so rarely, would appreciate some assistance from you guys!

i7 6700
GeForce 1080 founders edition
PSU: Corsair RM750X
Motherboard: MSI Z170A

have a lovely day!