HP A720n boots up and shuts down

[Pc Fixed Right]

I am working on a HP A720n Desktop machine. I absolutely have no idea what is wrong with it. The machine will boot up and shut down constantly, even on its own. As long as the power supply is plugged in it will turn it self on and off. I have put a new heat sink and fan on, new power supply, changed the ram, put it down to its most bare form for it to turn on and still the issue remains. I have applied thermal paste, all the fans are working but it just wont stay on. There are no BSOD it just turns off. Anyone have any insight or should I junk the machine.

 

[seedubya]

Any chance the MB is shorting to the case? Or a couple of blown capacitors? Considering what you've tried with the computer all that's left is MB and CPU.... If you can try a different CPU you'll have done all you can and can tell the customer in good faith to replace the system or at least the MB or CPU

 

[Pc Fixed Right]

Okay I replaced the cmos battery. The problem still presisted.

I than went with the computer might be shorting out somehow so I took the mobo out of the case and fired it up with the devices plugged in and the computer has not shut off or restarted in 4 hours. So the shorting theory might be accurate. I will let it run for a while longer and figure out where the short is. thank you for your help.

 

[seedubya]

You're welcome. Hope it turns out to be permanent.

 

[Pc Fixed Right]

The only thing I noticed was that I took the added on network card off the machine and that the bottom metal bracket on the card was slightly bent and possibly touching the motherboard near the bottom. I bent that back so that it should be straight, I put everything back together and the machine has now been running since my previous post.