PC not responding at all – no fan, no lights (check power supply first)

If the PC shows absolutely no signs of life – no fan spinning, no LEDs lit, no beeping – the cause is almost always the power supply, not an expensive hardware fault. Work through the following steps methodically and with an open mind before suspecting the PSU or motherboard: 1) Wall outlet: plug another device (a lamp, phone charger) into the same outlet or power strip – does it get power? Is the power strip's switch set to ON? 2) Power cable: firmly push in the thick mains cable at the back of the PC and at the wall; it comes loose easily – try a replacement cable if available. 3) PSU switch: many power supplies have a small rocker switch on the back of the PC marked 0 and I – it must be set to I (on); if it is on 0, switch it to I. 4) If the PC still does not respond after all of the above, the power supply unit may be faulty, or there may be a fault inside the case – this needs to be investigated and the component replaced if necessary (a PSU is a standard off-the-shelf part; if in doubt, consult a professional repair shop). Important: do not assume a switch or cable is fine or in a certain position without actually looking at it – these simple things are the most common cause. Do not bend any pins or contacts in plugs or sockets.