PC keeps rebooting

[Midground]

HP 580-023w PC tower will not stay on. Keeps trying to boot up over and over again. Turns on starts to boot up and then instantly shuts off. Starts booting up again only to shut off again. Tried reseating memory, graphics card and hard reset. Nothing works. PC still won’t stay on. 

[KrazyToad]

@Midground

Welcome to HP Community

I have gone through your Post and would like to help

Please run an Extensive System Test and let me know if it shuts down during the Test

- Shut down the PC completely
- Turn it back on, then tap the Esc key repeatedly until the Startup menu screen is displayed.
- Press F2 to select System Diagnostics.
- Click System Tests, then click Extensive Test.
 

Keep me posted

If the information I've provided was helpful, give us some reinforcement by clicking the "Solution Accepted" on this Post and it will also help other community members with similar issue.