The HP 800 G2 TWR PC turns on but shuts off after a few second

[Nasirjamil]

The HP 800 G2 TWR PC turns on but shuts off after a few seconds, and this process keeps repeating. It was properly shut down last night

[Bill_To]

Greetings @Nasirjamil 

Welcome to the HP Forum.

Try disconnecting the PC from AC power. Depress and hold down the power button, for a while, a few times to drain residual power from the MB.

Try to start the PC again.

This symptom is usually caused by a hardware problem.

It is impossible to isolate what specific component has failed in a Forum.

You would have to reduce the PC to a minimum configuration:

- Power supply

- Existing MB and CPU

- one stick of known good RAM

- Onboard CPU graphics, if the CPU and MB supports this option, or a different, known good, graphics card  

- known good PC monitor

A wild card problem could be a failing chassis power button.

You should test the installed CR2032 MB battery and replace if required.

You would now have to swap in different components, one at a time, (power supply, CPU and MB) to check for a successful POST if the PC will not start in a minimum configuration.

Swapping in different components is expensive. I recommend using a local PC Tech if your PC will not POST in a minimum configuration and the PC is out of the warranty period.

Regards