High pitched electric noise, coming from CPU on PC and laptop

May 31, 2018
Ive been looking through forums for hours now and cant find nothing. When idling or very light load both my thinkpad t420 and my i3 desktop makes the same very quiet electric noise. It is NOT the cooling, all the threads I read blamed it on the cooling but that cant be as on my laptop under light load its completely off and on pc I can turn them off so fans are ticked off the list of things that can make this sound. Saw someone saying that psus can make this noise, but Im not sure why my laptop does the exact same sound then... Does anyone know what causes this? Both are 2011 machines. Both machines run on standard temperatures both idle and under load, they are kept clean and maintaned. I dont think age is related tough, cause I heard my friends pc making the same high pitched noise, which is a brand new machine, built 3 months ago.