@Phaedrux that's a quite likely cause. I didn't have a part fan for a good while and I added one more or less at the same time this started to happen. I had a silicon sock on, but I took a quick look and it has a big hole in the side, next to where the parts fan blows.
Actually, I have to upgrade the part fan to a more powerful one I bought. I will upgrade it and have it blowing at full speed, if that's the cause then the problem will show up more often. Thank you!
