I remember an old Seagate Barracuda HDD from an old PC I had, it was so silent you would forget the PC had a HDD, shame newer drives click for everything now it seems.
I've had no problems with current Seasonic GX-650, I can't even tell when the fan starts. My system is pretty quiet with just the low humming of case fans / airflow audible.
What are the options for a quiet HDD nowdays? I see that SilentPC is using Seagate Iron Wolf NAS drives in their builds as optional and none else, they probably have a reason for it since all their builds are silence focused.