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The HP Community is where owners of HP products, like you, volunteer to help each other find solutions.
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Microsoft Windows 10 (64-bit)


I have a Z620 and 64GB of RAM and its a dual processor V2 machine.


I read that it can take mixed sizes of RAM but I'm struggling to understand where the 4 stiks of 8GB RAM I have will go alongside 8 x 4GB.




From the chart it looks like all 8GB should go on the CPU1 card. Is that correct? The machine I bought currently has 48GB of RAM with 4GB sticks everywhere.





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As I'm sure you are discovering the fine details of optimizing HP memory can be tricky.  And, there are other issues that are not detailed in the link you provide (which appears to be from before the version 2 Z620 release).


So, here are some issues:


What version is your Z620 you are asking about?  Version 1 or 2?  Boot block date 2013 vs 2011?


What are the two processors you are going to use?  Exactly.  Specifically, their sSpec code, which is laser etched on the top of each processor... on the stainless steel heat spreader.  Some of these Z620 processors only have one "stepping" but others can have two, and some even have three.  Start with what version of processor they are and make sure to include whether they are the v1 or v2 processors.


Are all the memory sticks ECC?  Are all the memory sticks buffered or not?


Ideally you will scan all of your 4GB and 8GB sticks so we can see what they are.  Then less confusion.  You need to put some effort in to this question you are asking.


Are these sticks all single rank?  All dual rank?  Half and half?


Are these sticks all the same speed?  What speed?  What different speeds?  


Do you know that one stick of slow memory will automatically down-regulate the speed of all the other sticks to match?  Do you know that one stick of slow memory will automatically down-regulate the speed of both of your processors to match no matter how fast they are?


Do you know a slow processor will automatically down-regulate the speed of all fast memory sticks to match itself?  For example, maybe all your 4GB sticks are 1866 and your processors are 1866 v2 ones, but one of your 8GB sticks is 1066 or 1333 or even 1600.... the advice will be different based on what you have for memory and what you have as processors.


Do you know that unless both your processors match and have dual QPI links you will never get them to work together?  That issue just came up here on the forum.


So, you are actually asking quite a lot... but it may be very easy to answer based on what you have.

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here's a quick rule of thumb that works for most dual socket systems when adding memory (but not the z620)


simply remember that the second cpu's ram banks should be the same as the first cpu's dimm placement


note that there are exceptions to the above rule which is why reading the memory guides is highly recommended


also some systems (not all) REQUIRE that the first bank of ram be the largest capacity


here's the official HP doc on z620 memory config (not all possible config's are shown)




look at the DUAL cpu 48meg config using 8 and 4 GB dimms and note the dimm socket order

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Thanks for your extensive reply.. it is indeed a bit of a minefield with the Z620s! Some of the questions you asked were answered in my original post. It's a V2 machine so it has a BIOS date of 2013. I know about the processors - they are matched, I'm just upgrading the RAM on this machine.


The RAM I have is 4 x 8GB 2Rx4 PC3L 12800R


Already installed are 12 x 4GB 2Rx8 PC3L 1200E


Hopefully it'll be possible to extend it to 64GB RAM but it's not the end of the world if I can't.






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Thanks for your advice, I'm new to these workstations and they seem to be powerful but...  temperamental!


Looking at the chart for 64GB RAM it's the same as the one I was looking at. Why is there only 8GB RAM in both rows for CPU1?


Is there an arrangement you can explain for 8 x 4GB and 4 x 8GB sticks?


Matching the CPU sockets makes a lot of sense to me, but the chart indicates the machine only wants 8GB around CPU1.



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L means the memory can run fine both at lower voltage or the normal higher voltage... but not in the Z620.  In there it will only run at the normal higher voltage.  I believe you can mix both L and non-L in these workstations, however.


You did not answer what processors you are going to use.  I don't need the sSpec codes of each.... just the exact processors.  This has to do with dual processor compatibility and also memory speed issues.


The PDF from HP you and DGroves refer to is from 2012, from before the release of the Z620 v2 you have.  Some of the info in there is outdated, of course, based on memory technology advancements, the Z620 v2 changes, and also the real world issues of memory cost then.  Cost constraints back then may not exist now.  For example, I've loaded up a bunch of Z620 v2 and Z420 v2 workstations here using recycled 1866 speed server memory 8GB sticks (14900R), all matching, at as low as 12-14.00/sticks (ECC, buffered).  HP info, eBay search experience, good timing, supply vs demand, make offer was the key.


ECC needed.  Can't mix buffered and unbuffered.  The E you mention in the memory codes generally means U, which means unbuffered.  How about a picture of one each of your 4GB and 8GB sticks?

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again,...................the z620 DOES NOT FOLLOW A NORMAL DIMM PLACEMENT (ie cpu 1 is a mirror of cpu 2 dimm placement)


look carefully at the memory picture on the document i linked to and note the slot numbering on the motherboard AND THE RISER CARD


then look at the 48GB ram section,


it shows two ways to do this one uses all 8gb dimms, the other way uses 8gb dimms AND 4GB dimms, both will provide 48gb ram however the all 8gb dimms will reach 48gb using less dimms IE-less sockets filled

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Thanks again for your help. The specs are as follows

HP Z620 - 2 x Intel Xeon E5-2620 V2@2.10 GHz 6C, 48GB DDR3, 200 GB SSD+6 TB

  • 2 x Intel Xeon E5-2620 V2 @ 2.10 GHz (2.60 GHz Max Turbo) 6 Cores (12 Threads) PER CPU
  • 48 GB DDR3 ECC Memory @ 1600 MHz (12 x 4 GB)
  • 200 GB Solid State Drive SAS (OS)
  • 2 x 3 TB Hard Drive SAS (Storage)
  • Nvidia Quadro K600 1 GB GDDR5 (1 x DVI + 1 x DP) Graphics Card
  • DVD RW Optical Drive SATA
  • Multi Card Reader
  • HP SAS card
  • On-Board Audio
  • Gigabit Ethernet
  • Microsoft Windows 10 Professional installed and activated
  • Windows 7 Licence Key on case (USED TO ACTIVATE WINDOWS 10)

Does this help at all?






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Thanks for your help. I hope to have a total of 64GB of RAM so I'm not sure why I should be looking at the 48GB section.


There are 12 slots... I have 8 x 4GB RAM and 4 x 8GB RAM I'm hoping to put in.



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you seem to have trouble understanding that i'm trying to show you the proper RAM INSTALL ORDER, the capacity will be determined by the size of the modules used


in other words if you have 4 dimms one size and 8 dimms of a different size , look at the chart and see if  one matches 4 dimms + 8 dimms

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