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HP Recommended
Microsoft Windows 10 (64-bit)

Hi everyone

Recently I have upgraded my Z840 (Dual E5-2630 v3- 1125W)
from 32GB (2x 16GB) DDR4-2133 2Rx4 Reg ECC (p/n 752369-581) to 64GB (8x 8GB) DDR4-2400T 1Rx4 Reg ECC (p/n 809079-581) there were no issues running the 64GB memory at 1866Mhz with the old processors
but after upgrading the processors to (Dual E5-2680 V4) the system won't boot and I get the 5 beeps
the 1st thing I have done before doing the memory/Processor upgrade was updating the bios to the latest version 02.56 Rev.A
Now it only works if I mix the old memory and new memory a total of 96GB Running at 2133Mhz
Populating the 1st memory slot for each processor with the 16GB DDR4-2133 Modules

I hope if you can help is it a comparability issue, faulty modules, memory controller, number of ranks ?!

HP Recommended

using non approved memory in your system can cause issue like you are having


ddr4-2400T means the memory is CAS 17 this may or may not work with memory of a different CAS


also using/mixing dimms with different "Ranks" in the same memory bank is not supported, each memory bank must be filled with the same Rank and capacity


the two modules listed below can not be used in the same bank, as they are different


32GB (2x 16GB) DDR4-2133 2Rx4 Reg ECC   (2Rank  module)


DDR4-2400T 1Rx4 Reg ECC (1Rank module)







HP Recommended

Thanks a lot for your reply I realize that there is a different part number for 8GB modules p/n 809080-581
which I don't have access to it at the moment, but if that will solve the beeps issue that would be great


I noticed that system boots fine with both E5-2680 V4 processors when the 16GB modules are populated in the

1st Dimm for each processor 

Z840 32G.jpg


The latest findings after cleaning/ swapping CPUs, reseating/cycling memory modules, are:

the system boots fine with the following memory configurations:

1st Scenario

CPU0 1x8GB 2400 Mhz Modules in slot 1

CPU1 None


2nd Scenario

CPU0 4x8GB 2400 Mhz Modules in slots 1, 3 ,6 ,8 

CPU1 None


3rd Scenario

CPU0 4x8GB 2400 Mhz Modules in slots 1, 3 ,6 and 8 

CPU1 2x8GB 2400 Mhz Modules in slots  6 and 8 


I get 5 beeps with the flowing memory configuration:

CPU0 4x8GB 2400 Mhz Modules in slots 1, 3 ,6 and 8 

CPU1 4x8GB 2400 Mhz Modules in slots 1, 3 ,6 and 8


Would that be because of an incompatible memory p/n , faulty/ incompatible motherboard, faculty processor with only 1 working memory controller ?


HP Recommended


the z840 default bios setting is for each cpu to have access to all dimm slots, as such if cpu 0 uses rank 2 in bank 3 then cpu 1 must also use rank 2 modules 

HP Recommended

Thanks again for your reply, no need for "CAPITAL LETTERS" if you pay close attention to my last post

I totally removed the 2Rx4 Modules, then in the 4 scenarios I have only populated identical single rank Memory Modules having the same part number (p/n 809079-581), speed (2400T) and manufacturing date (Year & Week)

I get five beeps with dimms 1, 3, 6 and 8 for each processor are populated with the single rank modules I mentioned earlier

In the 3rd scenario when I removed the single rank modules from dimms 1 and 3 for the 2nd processor the system boot fine. 


I removed CPU0 (E5-2680 V4) from the motherboard and replaced it with the CPU1 (E5-2680 V4 which in Dual Mode have only one memory controller working with channels 3 and 4) 

now the system has a single processor and the orientation of that processor has changed as I moved it from socket 2 to socket 1 and also the working channels has changed, with channels 1 and 2  (dimms 1 and 3) populated with identical single rank modules the system boots fine, but when I add  more modules to channels 3 and 4  (dimms Six and Eight)  I get 5 beeps!


So my question could that be a faculty processor, incompatible/faulty memory , incompatible/faulty motherboard ?!

The date of manufacturing of the unit is the 25th week of 2016

the motherboard A/N: 710327-002 REV 0C


HP Recommended

the memory controllers are embedded in the cpu,........check for bent pins in the socket also as i stated not all memory is tested as compatible since ddr3 ecc ram is so cheap used on places like ebay i simply use the correct recommended ram on these systems 


i had a z820 that worked with all sockets filled w/2GB dimms but did not see all dimm sockets if 8GB dimms were used this was traced to   "EC" cpu's someone had installed 

HP Recommended

Thanks a lot for your reply

The motherboard assembly number is: 710327-002 rev C and the boot block date is 07-02-2014 with the latest bios V2.56 and I have tried each of the following modules in dual processor configuration:

populating the 1st dimm for each processor 

 2 x 4GB 1Rx8 DDR4-2400T REG ECC p/n 809078-581      I get 5 beeps

 2 x 8GB 1Rx8 DDR4-2400T REG ECC p/n 809080-591      I get 5 beeps

 2 x 16GB 1Rx4 DDR4-2400T REG ECC  p/n 809082-591     I get 5 beeps

One of the processors (2016 batch) in single configuration mode (socket 1) and in Dual configuration mode (socket 2) works fine with all compatible and non compatible DDR4-2400T modules with all channels populated

the other one  (2017 batch) only works with channels (1 & 2) in single configuration mode and channels (3 & 4) in dual configuration mode 

both processors passed Intel® Processor Diagnostic Tool tests

I have tested the E5-2680 v4 (2017 batch) processor that had one memory controller working @2400 in the Z840 In a Dell precision T7810 (2017 production with bios v A34) it worked with 4 channels populated with the same HP DDR4-2400T modules, no beeps, was able to get into bios checked the processor and memory info, but didn't test further. It seems Dell has made a much better job with the latest bios update for the T7810!

Any clue about the possible cause of the issue ?







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