strange noise from pc

Yesterday night when I gaming I heard some strange noise came from my PC. Its like knock or pop sound(just like you tap your pc case like knocking a door). I heard it only one time but couple days back I heard sound like this too and when it happens pc was in idle. After sound there aren't any...

My pc started doing a strange sound idk but i think is the watercooler Where is the video View: https://www.youtube.com/watch?v=IxoTizHQbko&feature=youtu.be

Last year i started to have 2 issues with my pc, i have no idea what could case them, i even tried cmd scan and repair and i reinstalled windows but they are still there (so i dont think it is a software issue). First is: sometimes when i turn on the pc, some weird noise like a driving car is...

Will have any difference other than cooling?