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HP Recommended
HP Z8 G4 RCTO Base Model Workstation
Microsoft Windows 10 (64-bit)


I tried to upgrade my hp Z8 from 128GB to 384GB.

Originally there have been installed 8 SAMSUNG modules "M393A2K40CB2-CTD". (16GB ea.)

Now I added 16 original HPE Part-# 840756-091 (SK hynix) (also 16GB ea.)

When starting the machine I get a BIOS warning:
"Warning 17-1 occurred on CPUx-DIMM4 during memory initialization".

This applies to CPU0, DIMM 2, 4, 9, 11 and CPU1, same DIMM 2, 4, 9, 11 ... The memory size still is 128GB, but now using 8 of the SK hynix modules.

Strangely enough, when I remove exactly those 8 DIMMs I get a memory change warning to 256 GB ... Even though this memory configuration is not valid according to the manual ... I didn't check on speed/performance, but memory test works fine.

So I tried the following configurations (always identical for CPU0 and CPU1) ...

1.) 8 Modules in DIMM 1, 3, 10, 12 (128GB, Configuration I bought the machine with, supported by Manual Memory table)

2.) 12 Modules in DIMM 1, 3, 5, 8, 10, 12 (192GB, supported by Manual Memory Table)

3.) 16 Modules in DIMM 1, 3, 5, 6, 7, 8, 10, 12 (256GB, not listed in the Memory Table of the manual)

4.) 24 Modules in all 12 DIMM Slots of each CPU (384GB, supported by memory table, but System only recognizes 128GB, Warning 17-1 issued)

It does not really matter which modules I choose. If I fully populate the DIMMs I get the message. I swapped the modules as well to make sure that there is no faulty one.

I was not able to find much about this warning in the manual nor in the Internet.

Any guesses?

Best wishes,


PS: I also upgraded the BIOS to the latest version and cleared the settings ... still same behaviour.

HP Recommended

I don't know if you found your answer yet or if this will help but I had a similar problem with an old Z220, it's quite a different machine so apologies if my reply is just nonsense.

My problem happened when I paired two Hynix with two Crucial RAM together and received an error. Not the exact code you have however, but it was error code during memory initialization and it turned out that the Crucial was bad even though all modules were working a few minutes prior.

I also swapped the modules around to find a fault, only using Hynix worked and fired up with a memory change warning. Using only two Crucial modules did not post but either other one paired with a Hynix did and both gave an error during memory initialization test. They were almost 10 years old at the time so it wasn't too surprising that they gave up.

My apologies once more if my help isn't helpful, and best of luck to you, Capt. Caboose.

HP Recommended

incompatible memory, you cannot mix single/dual rank dimms in a bank, EACH BANK MUST CONTAIN THE SAME RANK DIMMS


SAMSUNG M393A2K40CB2-CTD is single rank memory


HPE 840756-091 is dual rank memory

(1x16GB) Dual Rank x8 DDR4-2666 CAS-19-19-19 Registered


A single-rank DIMM has one set of memory chips that is accessed while writing to or reading from the memory. A dual-rank DIMM is similar to having two single-rank DIMMs on the same module, with only one rank accessible at a time. A quad-rank DIMM is, effectively, two dual-rank DIMMs on the same module. Only one rank is accessible at a time. The server memory control subsystem selects the proper rank within the DIMM when writing to or reading from the DIMM.

Dual- and quad-rank DIMMs provide the greatest capacity with the existing memory technology. For example, if current DRAM technology supports 8-GB single-rank DIMMs, a dual-rank DIMM would be 16 GB, and a quad-rank DIMM would be 32 GB.

LRDIMMs are labeled as quad-rank DIMMs; however, they function more like dual-rank DIMMs. There are four ranks of DRAM on the DIMM, but the LRDIMM buffer creates an abstraction that allows the DIMM to appear as a dual-rank DIMM to the system. The LRDIMM buffer also isolates the electrical loading of the DRAM from the system to allow for faster operation. These two changes allow the system to support up to three LRDIMMs per memory channel, providing for up to 50% greater memory capacity and higher memory operating speed compared to quad-rank RDIMMs.

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