? How do you know you do not have a fault with your house wiring.
The fault could be anything from a loose wire, faulty plug socket/switch or even a faulty MCB. It could also be the power cable to your computer could be faulty.
1. Try a new power cable.
2. Try the computer at a different socket.
3. If you are using the computer downstairs try it upstairs as the are usually on a different fuse.
If you still have a problem it could be the power supply.