Question I have to turn my computer on by switching the psu on and off. It runs for a couple seconds then beeps and turns off.

[cade l]

It runs for around 3 seconds, all the fans and lights turn on, but as it is on there's just a long beep. Then it turns off. And to turn it back on I have to unplug and plug it back in.

 

[Impu7se]

probabbly when you disconnected your pc by switching off the psu switch it may have caused a short cut or something like that in the psu try twsting your psu if it works an example on corsair psu:

View: https://www.youtube.com/watch?v=5FWXgQSokF4