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Archived This topic has been archived. Information and links in this thread may no longer be available or relevant. If you have a question create a new topic by clicking here and select the appropriate board.

‎07-31-2015 09:48 AM

HP Recommended
Product: HP Z420
Operating System: Microsoft Windows 7 (64-bit)

We have a Z420 that will not boot. 

 

It returns:

 

929-Fatal MCA error.

CB0/LLC0 error detected CPU 0

Memory hierachy error

 

The Manual has no suggested fix.  Any Ideas?

 

Thanks!

4 REPLIES 4

‎08-19-2015 11:21 AM

HP Recommended

This could either be a memory failure (try reseating it, moving it to a different slot, or removing or replacing the memory), or a possible CPU failure.  (The system is reporting a CPU machine check error, but it could be caused by memory issues). 

 

Go into Computer Management, then click on Event Viewer, Windows Logs, and System.  Are there any WHEA warnings listed under Source?  An easier way to find them is to Filter Current Log, and select Critical, Warning, Verbose, and Error to filter out the (many) Information entries.

 

If the memory is OK, reseating the CPU might help, but this can be tricky.  The CPU socket pins are very easily bent during the removal or install process, and extrememly difficult or impossible to repair if damaged.  Also, when the CPU heatsink is removed, clean off the thermal paste on both the CPU and heatsink, and use new paste.  The paste hardens, and does not give good thermal conductivity if the heatsinks is removed and the paste is not replaced.  The CPU operating temperature can increase by 10 deg. C or more.  FYI.

 

If the system is under warranty, contact HP so they can fix it. 

I am an HP Employee.
My opinions are my own, and do not express those of HP.

Please click "Accept as Solution" if you problem was solved. This helps other forum readers.
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‎08-19-2015 12:37 PM

HP Recommended

Thank you the reply Dan_WGBU ,

 

I did try reseating and replacing the memory but as the PC is under warranty I did not touch the CPU. 

 

I will begin the warranty repair request.

 

 

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‎07-28-2016 08:59 AM

HP Recommended

Hello,

Did you ever get this resolved? what was the resolution?

We have this same issue.

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‎09-21-2016 09:56 AM

HP Recommended

We have seen replacing system board has fixed the issue.

In rare cases processor.

I am a HP Employee
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