power supply

A Power Supply is in a Computer, and provides power.
Watch out! some Noname Power supplies are chinabombs, and will explode within some years!

My Power supply exploded, i think i should by a new one.

mainboard

Mainboard (or Motherboard) is used in your PC, all of internal components are on it.
(CPU, GPU, Soundchip, and some other devices)

PS: A computer is used to download porn :)

I want to buy a new Mainboard, maybe my PC would be speed up....