Question HP Z420: Power Button Lights-Up When Pressed, but Doesn't Power-On

[JudithWright]

HP Z420 Workstation:

CPU: INTEL XEON E5-2670
RAM: 32GB ECC Memory
GPU: NVIDIA K600
SSD: 128GB Boot Drive
HDD: 8TB Archive Drive
CMOS Battery: New

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HP Z420 Workstation powers-on just fine if I Press the CLEAR CMOS Button and then plug-in the power cable (system turns-on automatically).

When turned-on in this way, the system seems to work normally, and I was even able to install Windows 10 and download all of the Updates with no problems.


However, when I try to re-start the system (to install the updates), the system just shuts-off and will not turn-on if I press the Power Button.

The Green Light on the Power Button does turn-on when the Power Button is pressed - but nothing else happens.

If I want to turn-on the system, it seems that all I can do is unplug the Power Cable, press the CLEAR CMOS button on the motherboard, and plug-in the Power Cable.


How can this be fixed?

I do have 2 other HP Z420 Workstations that have their own separate issues and can be used for parts.

 

[Lutfij]

Is the PSU in the system with the issue, from 2012(when the prebuilt was first released)?

 

[JudithWright]

Is the PSU in the system with the issue, from 2012(when the prebuilt was first released)?

I'm not sure -

The system does seem to run just fine when the CMOS is cleared and the Power Cable is plugged in -

If the PSU was the problem, wouldn't there be signs when the system is running that way?