PC turning on problems. PSU issue?

[Mutley]

Odd problem and only happens with turning my PC on. I press the on button, it boots up for 5 seconds, then shuts off (like it looses power). After normally 3 trys, it boots up fine. I thought it might be the PSU not supplying enough power to components? It can also have an effect on USB components like modems, with low power, shutting off.

How can I check, fix it?

 

[NeptuneUK]

new PSU, unplugg ur CD drives and everything USB + everything else that uses power that u dont need. see if it works ok. if it does. get a new PSU. you dont have to break the bank on a PSU, but you cant cheap out on one

what PSU have ye now?