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HP Recommended
HP Z840
Microsoft Windows 10 (64-bit)



We have the exact same issue as described here:



This topic was never resolved so I am hoping someone can help. 

Bascially the machine will boot up with 2 x 8Gb 2400 DIMM's (Approved Ram) but as soon as we load 4 or more sticks in, it fails to boot and gives 5 Red Beeps.

  • It is using Dual E5-2690-V4.
  • It has the latest BIOS
  • All sticks are matching capacity, size, speed, part number etc. 
  • The CPU's, and Motherboard pass diagnostic tests. 
  • I have observed the loading configuration / order etc. 

It was prevously working fine with Dual E5-2643-V3 and 32Gb of 2133 Ram (8 sticks of 4Gb) and we are trying to upgrade it. 

Any idea what this could be? 



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memory errors on  a z840 are almost always due to


improper dimm placement (wrong socket order)


incorrect ram modules such as non ECC when ECC is specified or using low powered "L" suffix ram


mismatched ram  such as mixing 2rank and 4rank modules in a bank, or mixing ecc/non ecc ram


a actual defective ram module


a defective ram socket


bent pins on the cpu socket (only applies to cpu's with embedded ram controller)


also when asking for help, posting the items model information should always be done!!









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Hi DGroves, 


Thanks for the help on this, please note the following:

  • We are getting this error on a number of machines
  • We are also trying to upgrade the CPU to a 2690 V4
  • All Bios have been updated to very latest version. 
  • I'll post model info shortly. 

I have checked the following:

  1. Dimm placement is correct
  2. Ram is all ECC and not L Suffix (We have tried 3 different brands, all HP Part numbers, etc)
  3. Ram is all the Same Bank, Brand Etc
  4. I have checked the Ram into another z840 that is currently running a V4 Cpu and 2400 Ram is it all works correctly. 
  5. If I take 2400 ram from a working machine and put it into these into the machines and get the same error
  6. If I boot the machine up with a single CPU and a single 8Gb stick, the machine boots fine. 
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In addition, if I try to boot the machine up with a single CPU and more than 1 stick of 2133 ram, we get the same error. 

I have also tried reseting the Bios using the motherboard button as per HP instructions and still no joy. 


Everything points towards an issue on the system that is not accepting the V4 CPU's and ANY type of ram. The only way to make it boot is with a single CPU and a single stick of ram. 

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second time,......please post ram module information without the dimm module numbers being used it's very hard to rule this out

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I don’t have that information to hand, but will post tomorrow.
But surely because i have tried multiple types of ram (mixture of 2133 / 2400 and 8 /16 GB sticks), all from working z840 machines (mixture of units with V3 and V4 CPU’s) then we have ascertained that it’s not because of an incorrect / mismatched dim? 

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And to be clear, when I say “tried” I’m not mixing the ram up! This is swapping the entire set of sticks from a working machine to one of the non-working machines. 

The only way to get the “non-working” Z840’s to boot, is by having 1 stick per V4 CPU (this works regardless of 2133 or 2400 Speed). 

HP Recommended

since you will not post the dimm part numbers, i'm going to end this and move on perhaps someone can still try helping you

HP Recommended

Did you actually read anything that I said?


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