PINE64

I just bought a rockpro64 board to build myself a little NAS (for fun and education purposes). However, I've noticed that when the rockpro64 is plugged in and running, it makes a buzzing sound. Not too loud, but audible if I put my ear near the board; makes me concerned about a faulty capacitor. Is this normal? Does anyone else hear this?

I've tested this without any components plugged in (except an emmc module). I'm using the 30mm tall profile heatsink, and the stock sockpro64 12V 5A US power supply.

Just want to make sure I'm not going to have a problem with the board soon (or fire hazard)! Let me know if anyone has experienced this or if I should try to send it in for replacement.

Thanks!

Many of electronic devices are equipped with DC/DC converters. And may be in more than a half cases you may hear the vibration of converter components being very close to the board. Usually these sounds are quite enough to be not noticeable.
If you hear the sounds at a distance, say, 0.4m, it is unusual. I'm hearing none from mine ROCKpro64. You may try to touch and slightly press the inductors and the capacitors on the board, one by one, to determine which component is most loud and is changing it's sound when being touched.