Their benefits are such that it’s become surprisingly rare to see a traditional linear power supply with a mains-frequency transformer and rectifier circuit, so [ElectroBoy]’s dual voltage PSU ...

There will also be a standby 5V supply using another small transformer, and a “power good” circuit to tell the motherboard that the PSU is ready and to activate the supply on an external input.

Power supplies known as "switching" power supplies are commonly used. Their name is derived from the type of circuit used to change the voltage. For more details, see transformer. See power adapter.