Hi Tobias,
what about your PSU?
during 1 month I analyse a lot of PSU, and you know what? All that I have tested do the same " buzzing , coil whine , or other zzzzz" and I think it is normal!
All begin when I decided to change my motherboard , only cosmetic reasons .. I had gigabyte z370HD3P with i7 8700K ( I never OC) and I change for ASUS Z390E , then I decided to buy a better PSU ( I had evga 600B , 1 year , 100h max ..)
After a lot of search, tier list, reviews, I choice corsair RM650X, receives my Rog mobo and the corsair, mounted 1 day with lot of attention, then power on! and all seems good, no noise.. I power off, and put my head behind the PSU!! zzzziiziiiziiiziiiziii , when pc is on this sound dissapear. and when pc is on standby this sound is more important.
I had time to send it to seller, but after a lot of labour to mount cables .. I decided to contact corsair, they answer after 3 days " your rma was accepted" , I asked them again " why? , I don't want to rma it" they say " this psu is faulty" I asked " which one I have to buy? all your psus RM are faulty? a remplacement will resolve this issue??, they don't answer.
I return this rm650x to seller ( lost 10 eur)
I try an EVGA 650 G+ , the better that EVGA made by FSP group.
result: the fan is too loud, always 750 rpm. and I listen ziiiiiii when the psu is working on game. RETURNED
then I try my chance with an RM750x ( made by TWC, the 650x is made by seasonic)
result : exactly the same, perhaps a little silent ziiii than the 650x , but this one is doing this noise when on and off,
If I don't put my ear behind the psu I heard nothing ,
I asked corsair again, but I think that all this psu doing that " electrical noise" that not means they are faulty, I hope...
I don't say my last word, I don't know if I will keep this rm750x , I don't need so much power , i7 8700k and rtx2060 max Watt is near 400W .. 550w is enought