Gateway 450ROG Intermittent power up failure

Gateway 450ROG SN: 0031598515 powers up only intermitently after many attempts. I hear a single click, power lights flash and then almost immediately another single click and it try all over again. Sometimes well into the boot cycle, sometimes immediate. Same issue when starting using a Linux boot CD, with and without battery, different power adapters, etc so not a software issue.
Sometimes after many such attempts it will start and if I don't touch or move the laptop it will run for days using remote laptop and mouse. Is there a internal power supply that can be replaced or is this just a motherboard replacement issue?
Thanks for you help,
Dennis