Will 16GB RAM work in an hp Z620?

[Buffalo_Rider]

I have seen conflicting information about what memory sizes the hp Z620 will accept.  

I am only talking about Registered ECC memory in this post. 

On a post on these community pages from April 2017, the responder (BambiBoomZ, writing to AitorLopez) said the Z620 will take 8GB memory cards as the maximum size.  This suggests or means it won't take 16GB cards.

On a post on these community pages from  November 2019, the responder (Brian 1965 responding to Mo7amed7) said the Z620 will take 16GB memory cards. 

Crucial Memory sells 16GB memory cards for the Z620.  Page 28 of hp's Service Guide says that the Z620 takes “1600 Mhz 4, 8 GB ECC Registered DIMMS”; there is no mention of 16GB DIMMs.   Page 11 of hp's QuikSpecs says the Z620 will take 4GB, 8GB, or 16GB Registered ECC Memory Cards.  The information in the Quikspecs is in other places in hp documentation.  The information on page 28 of the Service Guide - I saw this for the first time today. 

I am confused.  I bought  four16GB cards for my Z620 based on the hp documents - and I felt I scoured them pretty thoroughly - and installed them and the computer will not power up.  I turned it on, it was quiet (the disk drives were quiet), and then after perhaps a minute or so I heard a beep.  The display was never engaged by the video card.  So I pushed the power button and it went off immediately, showing that the OS had not started.  So I am trying to figure this out.  One of my first thoughts was - maybe the problem is the memory.

Anyone know definitively how I can find out if 16GB is supposed to work in my Z620? 

[Buffalo_Rider]

An update:

I removed the second processor, then powered on the computer as a one processor Z620.  I had two of my four recently purchased 16GB Registered ECC memory cards installed.  The computer came up and it shows it has 32GB installed, as I would have expected since it powered up.

So 16GB RAM will work in my Z620 - and I assume it is supposed to for all Z620 variants, but I don't know for sure.

Next step I guess is to plug in the other two memory cards onto the one-processor motherboard, and see if it works. If so, then I know the memory cards are good.  If not, then perhaps I have a defective memory card.

[Buffalo_Rider · Accepted solution]

Second update:

Bottom line is that everything is now working. 

I re-plugged in the second processor board, with the additional two 16GB memory cards on it, now that the system was working as a one-processor workstation.  (Rather than methodically checking out each of the two remaining memory cards).

I then powered it up.  It took some time to come up because it was downloading and installing Windows 10 updates at the same time, but it eventually got to the Windows screen.  I right-clicked on the Start icon, then clicked on "System" and it came up showing I had 64GB installed.  All four 16GB cards are being seen by the system.  I also checked it by clicking on the spyglass (next to the Start icon), typed in "msinfo" and hit enter which brought up the System Information Window.  It also showed 64GB.  So problem solved.

Besides getting it running first as a one-processor workstation, I think what also helped was getting the monitor to work.  The monitor, connected to the workstation by a DVI cable, needed to be reset through a power off and power on.  When I powered it up as a one-processor workstation, I could hear the arms in the hard disks accessing data so I knew the Operating System was being accessed, but nothing was displaying on the screen.  So I turned the monitor off and then back on and then it began displaying the Windows screens.  When I re-plugged in the second-processor board and powered up the computer again, I did not turn on the monitor until I heard the disk drives operating. 

So problem solved, and my question got answered.  Yes, this Z620 will work with 16GB memory, and I suspect all the variants of the Z620 will.  I do not know why p.28 of the Service Manual did not include 16GB in its list of memory that will work on the Z620. 

[Buffalo_Rider]

The problem was fixed. I summarized the solution here so others could benefit.

Somehow it got marked as spam.  I asked the moderator to restore it. 

[Buffalo_Rider]

I ran Microsoft's Memory test on my 64GB of  RAM memory cards - it took a couple hours - but it finished saying the memory cards were all good.