Broken pc

[43trombones]

My pc will turn on then about 5 seconds later will turn off then 5 seconds later turns back on again and it will do this till I turn the psu off please help

Link to a video of the problem:

 

[Cycloid Torus]

Can you access system setup ('BIOS")? If so, turn off 'automatic restart on error'.

If not, then you have a difficult problem... and this may help: