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HP Recommended

So I'm just posting to complete what this poster started a few months ago regarding memory upgrades:



I have been able to install 32 x8 LRDIMM modules for a total of 256GB of RAM. 🙂  The modules I used are the following:

hp 712384-081
samsung m386b4g70dm0-cma4qm
32gb 4rx4 pc3-14900L-13-12-c0


Other modules may work. I was able to run at max ram speeds of 1333 since that is the max my processor (E5-2630L) can do. I believe speeds would be faster with the processors that can handle 1600Mhz.  This is faster than the clocking down that may happen with 32GB RDIMM modules.


Cooling may be an issue however as I ran into memtest errors after about an hour. Even though I keep all the fans floored by setting the bios fan idle to the highest setting, the modules in the sockets between the processor and drive cages was too hot to touch while the cpu and other modules were fine. I’ve added another fan to make it pass the memory test. I’m not sure if I will need it in normal use.

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For years we have been discussing the significant differences between the older slower version 1 of the ZX20 workstations versus the newer faster version 2 ZX20 workstations.  The idea that the v2 can run the v2 processors, which can run faster..... 1866MHz processors and 1866MHz memory.


The brochure above is for the old slow v1 workstations, published back in 2012.  There are better resources available from HP that present the recommendations for the v2 workstations and the 1866MHz capable processors/memory.  To the OP.... do you have a stock HP front cooling fan in place?  Do you have the optional airflow guide for memory cooling HP made for that workstation?  I can get you the part numbers and the more recent memory guides if you'd like.

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Why?  That document is completely wrong.


I am running 4x the maximum listed in that outdated document.  Systems regularly sell on ebay with 128GB installed. 


My post was to let the community know that 256GB RAM is possible in the z420.


Also my memtests are working without any overheat issues once I put a small fan near the other memory slots.  I'll probably buy a commercial memory cooler and that should prevent any issues completely.

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Precisely.  It's like everyone in the world knows the full capabilities of these older systems (hence why they still have a lot of value) except HP, who made them. 🙄


Do you have a link to the v2 documentation?  I'd be interested in seeing that as I didn't refer to it before making my hypothesis on if these modules would work.


There is no stock front cooling fan, which I believe would help somewhat.  What does the optional air flow guide for memory look like?  Part numbers and some information about the guides would be great!

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Thanks for your work on the Z420 maximum memory.    It has proven to be the equivalent of the Z620 in terms of virtually all parameters except that it cannot run two processors simultaneously.


Agree on the value of presenting documentation that is up to date, at least as much as is possible.  The links below will help.... they include the transition from the ZX20 version 1 to the version 2 workstations.  The 1866MHz memory means one has a v2 processor and a v2 motherboard.  Take a look:


*****NOTE: THESE ALL DO WORK AS OF 2/23/20*****

HP DDR RAM QuickSpecs for workstations... these include memory for the Version 2 ZX20 workstations.

http://www8.hp.com/h20195/v2/getpdf.aspx/c04164501.pdf (gets only the latest (v6) of HP DDR RAM QuickSpecs)

http://www8.hp.com/h20195/v2/getpdf.aspx/c04164501.pdf?ver=1 (get v1-6 of DDR RAM Quickspecs)







Regarding the front memory air duct.  This is a passive device that uses the fan in the power supply to direct airflow in from the front and up over the front memory and out through the power supply:  Look up 663346-001.  The Z440 has a powered set of memory fans suspended in the device.  Also consider my discovery of the double surface area heatsink/fan that is used in the Z440.  It works perfectly in the Z620 and Z420.




The front case fan is worth having:    Here is a copy/paste about that:


Z420 Front PCI fan & card guide *kit* is comprised of fan holder & fan = 684024-001.

Z420 black plastic fan holder part has AS P/N 604781-003 etched on the plastic which
is ***identical*** in shape to the one used on the Z400 (which has AS P/N 604781-001
etched in). These likely also would work perfectly in the xw4600.

Z420 fan is a Nidec, also used as the 92x92x25mm fan for other purposes in the Z420.
This has AS P/N = 647113-001 REV A, and has OEM label of T92T12MS3A7-57A03, which is
a 0.35A 12VDC fan and runs at 629 RPM in the Z420 v2 (which is excellent). Do not
know the RPM if that fan is used in the front PCI position in a Z400.

I have seen the same part number on a HP Delta fan which stated it was 0.60A, the
QUR0912VH, but would stick with the Nidec fan due to its lower amperage.


Thus, can search for the following numbers and buy the least expensive one. I have also
found that eBay sellers sometimes use the fan part number to sell the whole kit so search
using that also:

Z400 619579-001 SP P/N (HP calls this "Cooling fan kit with front guard & fan")
604781-001 AS P/N for the black plastic part
xxxxxx-xxx fan

Z420 684024-001 SP P/N (HP calls this "Plastic front card Guide w/fan holder)
604781-003 AS P/N for the black plastic part
>>>>>>> 647113-001 fan (this Nidec fan in Z420 runs at 629 RPM.... excellent)

Best deal via all these was by searching for the fan number from the Z420, and both the
fan and the black plastic holder were included, for 15.00, shipping included.



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A bit more..... yes, I too have experimented with retired server ECC registered HP RAM in my Z420 v2 and Z620 v2 builds.  Works fine.  Never went up to 32GB sticks, but can say that I've only used the fastest (14900 = 1866MHz) sticks.  Those have worked also in Z600 v2 builds, happily, because they are built to down-regulate their speed automatically.  This won't work in a Z600 v1 because it has an older memory regulation scheme.  This recycling is a good thing.


You could likely run your 14900LR sticks at 1866 if you had a 1866 (v2) rated processor in your v2 Z420..... say, E5-1660 v2 which we use now in our Z420 builds.  E5-1680 v2 gets spendy.  Running that memory at 1866 would be worth the effort.


Heat..... your experience shows that adding in that front air flow guide likely would benefit you specifically.  It is your front bank of sticks that are getting too hot.  That is what HP designed that guide to take care of.  Front fan too.... you need that kit.


My recall is that in the QuickSpecs for the Z420 HP mentions you can run L rated DDR3 sticks but that they will run at 1.5VDC rather than what they can do in other situations (1.35VDC).  Do you have any HP part numbers for L rated 16/8 GB sticks?


Finally, remember HP's market for these workstations is Enterprise, not experimenters like you and me.  We need to self-validate out in the wild and I appreciate your sharing the info.

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Thank you for the great additional information! 


I'm surprised I didn't find the front memory air guide for the z420 as a quick search brought up a picture of it installed.  I wonder however about the amount of heat going through the power supply this way and the additional stress it puts on the power supply components.  After all, the power supply isn't exactly an off-the-shelf item if it goes bad.  (Speaking of which, I know where to get a complete case with 400w power supply and the rear and memory fan shipped for a good deal if  someone needs one.  I got mine the same place.  Just message me.)


I couldn't find much with the memory duct part number 663346-001, but I was able to find a lot more supply with 663070-001, which looks identical from what I can tell.  I was thinking about the z440 hsf combo as it would move more air across the front memory and keep the cpu even cooler at the same time, but I don't want to affect the rear fan assembly since the z440 memory fan assembly seems like a bit of bear to retrofit to the z420.


I looked at the prices for the front fan and the best I found was well over $15. 😞  Unlike Dell that seems to have overproduced parts for their systems over the years so there's lots of spares out there, HP did a better job of just producing enough, so now the parts are rare and have increased in value.







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I never even thought about trying to upgrade the memory in my v1 system since it already came with a healthy 32GB and I didn't expect I would use any more.  But once I found out it could take registered and I had some LRDIMMs lying around, I decided to run a little test--and it worked. 🙂  It is unfortunate that I don't have a v2 because LRDIMMs would run at the full 1866 even with all the channels full (no clocking down).  But it's okay.  This was a surprise for a system that I expected to just be good at what it was doing and nothing more.


Yep, I've been looking at these now, but honestly it's much cheaper to just leave my fan pointed at the memory for now and just get an aftermarket memory cooler that will snap on the dimm sockets.


I think I may have some PC3L modules, but none that are 8/16GB.  Well, wait a second--I think I have a pair of 16GB PC3L-14900r in my Dell R410 server.  I'll see if I can't try those once I'm done with testing the LRDIMMs.


Yep, these are well-built and engineered enterprise machines.  Hence whey they're still being pushed beyond their original design and with great reliability. 🙂  Kudos to HP for making these as well as they have.

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One thing I forgot to point out when installing this memory is that you should be very patient at boot--it takes my system up to 1 minute before it shows it POSTing.  I have my idle fan set to the highest setting so that's when I know it's about to boot--might be a useful trick if you upgrade to this level.

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