Spent more than on hour scared, trying to figure out what was wrong with my laptop after I cleaned it and reapplied thermal paste. Long story short, I had just put RAM into the incorrect slot. Idiot.
The result isn't anything spectacular either. sensors keep showing CPU temperatures around 40 degrees, which is way too much IMHO, although I didn't check that stuff before... Yeah, I'm an idiot. Moreover, it seems that the fan produces high-freq noise that I can hear only with my left ear, not the right one. I'm getting deaf. O_o°