I don't have PSU to swap for the moment, I think I am going to use warranty on PSU.

However, I would like to be sure there is some issues with PSU.

What happens when trying to start off the rig by pushing power button is : just hearing a small electric sound in the PSU. If I press a second time the sound doesn't repeat.
Then, after pressing and holding the power button a long time (as if I was trying to shut down the rig), I can hear the same sound again when I press the power button again a short time.

Who can from that information guide me to be 100% sure this is PSU problem?

Thanks