I am trying to diagnose a client's PC. Previously their PC wouldn't stay on, it would just turn on and off repeatedly (while passing POST). They ordered a new power cord (by my recommendation) and now it will only stay on for 5 minutes at the recovery menu before shutting off. Client says it has to be manually turned back on. I know this may be a newbie fix, but please help; An OS install is needed as well and I dont' know how long it'll stay on during the installation and I don't want to risk ruining the hard drive. Need info by tomorrow morning as the client wants it fixed then.