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Z420 constantly power cycling.

HP Recommended
Microsoft Windows 7 (64-bit)

I recently patched a Z420 running Windows 7 (64-bit). I restarted the computer, and then the issue started.


The system turns on (Blue LED Power button, DVD drive spins, etc.)  after 1-2 seconds it shuts down, waits 5 seconds, and then starts again. If I remove the power plug, it still tries to start up again. It fails (becuase no power) but the LED power button  turns red and a BEEP code sounds off. The BEEP code varies between (3) options:  2 Long, 2 Long & 1 short, and 3 Long. After many tries to identify I can tell the BEEP code is completely random between the (3).


The only thing that does seem "off", is that the PSU fan sounds like it is struggling for that 1-2 seconds of activity.


Any thoughts?

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Message 2 of 2
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HP Recommended


Welcome to the forum.

I am not a HP employee.


What patch did you apply?


Your PC's chipset is from Q1'12. I am guessing your PC was manufactured in 2012 or 2013.


This HP Support site list BIOS error codes for various HP products (Link). I don't see any specific beep and LED blink error codes for PCs made before 2015 that exactly match your description.


There are some LED blink codes and some combo error codes.



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