Glacialpower GP-AL 650A Power Supply @ Mikhailtech
 

On the inside of the power supply we see that the coils are well protected in different ways, so they won't make a humming noise while on load. Also, the fan wires are protected with a plastic tube, so it does not get damaged when the interior of the power supply gets hot. I appreciate that the fan is not soldered directly to the power supply PCB, it has a plug and you can unplug it very easy and replace it if it fails.