Power on then off

[Forrest83]

Hello everyone. So desktop been down for awhile. I'm not even sure what happened. My daughter said it wouldnt turn on. 

So I started checking it out this morning. I'm computer illiterate so bear with me.  Pushing the power button fans start HP appears on the monitor then computer powers off after couple seconds. Same if disconnect and reconnect power. 

So I'm leaning more toward the external power supply or the motherboard. 

Case is a little dusty. Cant see anything on the motherboard. No burnt smell. Removed cmos battery. Thanks for any help

[Grzwacz]

Greetings,

Welcome to the forum.

I am not a HP employee.

Excessive dust can cause problems. Clean internals with compressed air or a dust buster. Let the PC sit for quite a while before reassemble and a power on test. Moisture and electricity are not a good mix.

Yes, the external power supply is a possible cause.

I would try starting the PC with only a mouse and keyboard. Then try starting the PC with no peripherals (mouse, keyboard, or printers, and external USB drives connected to the PC.

A system short can cause this issue. A short can be caused by excessive buildup of dust on the MB or components connected to the MB.

The short can also be caused by a peripheral device connected to the PC (bad port or bad device) or internal components connected to the motherboard.

I would start with the power supply after: a good cleaning and removing all external devices connected to the PC.

Work your way down to the motherboard.

Regards