Z840 512GB memory configuration

[Scoobis]

I have a new to me, HP 840 on the way to me.  

i two questions aobut the memory config -

what the official hp config recomendatons are for 512gb,

and second Is what i think the real confiuguration requirements ofr low burden dims correct.

i have rad all the docs and quick specs i could find, but i foudn the information conflicting and not clear.

I would like to configure it with 512GB of memory.  i have 8 dimms of HP 32GB (1x32GB) DDR4-2400 ECC Reg RAM T9V41AA already.

i am unsure if i can use another 8 T9V41AA to make 512 or if i must to get a 8 HP 64GB (1x64GB) DDR4-2400 ECC LR RAM T9V42AA for it to work.

also I  would like to know if anyone has tried using 16 HP 32GB (1x32GB) DDR4-2400 ECC Reg RAM T9V41AA and if so, what happened. 

why i find the informaiton confusing in the docs i can find is the only low burden memory is the 64 gig modules )in quick specs, but, they do show configurations for 16 32 gb modules in the manual. also. in the manual (whih i relize might have been written befor the moudles were avialable) says that the max memory is 256gb before needing  low burden memory, though, i am gussing that mgiht have been 16 x 16gb modules when the manual was written i am guessing.

It appers to me that the actual restrictions is probably that you can do 1 and 2 rank dimms in the 16 slots, but, if you go to more ranks like 4 rank or 8 rank dimms you need to use low burden memory.  i say this only becase thats what i have observed on other systems using the same processors and chipset (processors has the memory controller in this case). Perhaps somone could confirm or disprove the rank aprach to the system configuration over what the available docs seem to indicate..

quick specs did not make thigns any clearer for me  btw. 

i apreciates any insights people have and expereinces, and also the official postion form hp if known

[DGroves]

 the HP z840 memory load order is shown on the inside of side panel where each dimm socket will be marked with a number showing proper placement of each group of 4 dimms

each cpu  has 16 dimm sockets available

to reach max ram capacity

or use the other 16 mem sockets

a matching second processor must be installed

the system supports a maximum of 1TB with a single CPU using 128GBLR dimms

and up to 2TB with the dual CPU configuration

each cpu bank will take 16  dimms  in groups of 4 each group of four can be a different memory size so you can install 4 32gbLR dimms in the first 4 mem slots and 64GBLR dimms in the sec group of 4 dimms

note that the dimm memory  load order and dimm capacity must match for each cpu's  memory sockets

each cpu has 4 memory channels

adding the sec cpu will also activate the white pci-e  slots on the motherboard

to use 32gb or smaller  dimms, they must be ECC normal or load reduced dimms

be aware the system will not work with mixed LR/normal dimms

dual 130 watt or higher cpu's require the optional 1120 watt power supply per HP

https://www.compeve.com/Documents/HP%20Z840/hp_Z840_quickspecs_compeve.pdf?

[Scoobis]

@DGroves first thare are only 8 slots per cpu not 16 - there is a total of 16 slots, 8 per cpu and yes 4 channels

i'm not sure if you addressed either of my two questions. but let me ask directly aobut the uestion you seem to ahv posted about

Is your answer that i can or can not use 16   32GB dimms that are not load reduced?

[DGroves]

again, you CANNOT MIX load reduced dimms and non load reduced dimms it' one or the other

and yes you are correct on the total number dimm sockets (that's what i get for posting at 2AM in the morning!)

[Scoobis]

@dgroves  - lol i have been there in posting at 2am.

i dp not think you are reading the question as i intended it. - i am not talking about mixing memory types..

i am asking specificly about using 16 dimms of HP 32GB (1x32GB) DDR4-2400 ECC Reg RAM T9V41AA which are not load reduced dimms in a Z840 Is that an accepted HP configuration?

Can I use 16  HP 32GB (1x32GB) DDR4-2400 ECC Reg RAM T9V41AA  dimms in the Z840? 

[DGroves]

the answer is most likely yes

HP can only qualify a small set of existing dimms and can't test modules that were not yet in production when they were qualifying ram for the z840

the HP 32GB (1x32GB) DDR4-2400 ECC Reg RAM T9V41AA  dimms are 2Rx4 - Dual Rank x4 dimms  and as long as any existing 32GB dimms are also dual rank there should be no  problems

in a nutshell as long as the mem type (ddr4 in this case)

and  registered ECC of a official JDEC speed (2400 in this case)

and each dimm in a memory bank is the same rank (you state all will be the same  T9V41AA)

then it should work fine you only need Load Reduced dimms for 64GB or larger dimms for 32GB or smaller dimms it can be either normal non load reduced or load reduced and i'm not currently aware of any "RETAIL 32GB LR dimms but they may be available for OEM uses

[Scoobis]

thanks for being patient dgroves.   I have a good udnerstaning now.