Good day to everyone - this is my first post here and am trying to solve some memory issues with a newly purchased
HPZ4 G4 workstation.
I purchased a used HPZ4 G4 and it came with 32GB memory - (4) 8GB DIMMS that were installed in DIMM slots labeled DIMM1, DIMM2, DIMM7 and DIMM8 on the system board. All was fine and I had no problems configuring the workstation or its performance - it was a big upgrade from my 10 year old HPZ400 workstation!
I decided to upgrade the memory to 64GB as I want to run a couple of VM's and picked up another (4) 8GB DIMMS. The additional DIMMS were Lenovo branded but had the same Samsung PN as the HP branded DIMMS. So now the 8 DIMM slots on the system board are fully populated with
Samsung 8GB 1Rx8 PC4-2666V-RD1-12-MAO DIMMS.
The issue is that the system BIOS only recognizes 6 of the 8 DIMMS and reports 48GB memory - it completely ignores the DIMMS in the slots labeled DIMM3 and DIMM4 on the system board.
Here's what I have done to troubleshoot so far:
1) Plugged the HP branded DIMMS into the DIMM slots they were originally installed in (DIMM1, DIMM2, DIMM7, DIMM8) and the BIOS reports 32GB memory
2) Removed the HP branded DIMMS and plugged the LENOVO branded DIMMS into the same DIMM slots (DIMM1, DIMM2, DIMM7, DIMM8) and the BIOS reports 32GB memory
SO - after 1) and 2) - I'm feeling I don't have any bad DIMMS.
3) Removed the CPU and checked for bent pins on the system board - none found.
4) Replaced the system board with a new system board - same exact issue.
At this point - I have to admit that I'm a bit puzzled. I know that there is an optional memory cooling fan for the HPZ4 G4 - which I do not have. Is the memory cooling fan required when all the DIMM slots are populated with 8GB modules? I thought it was only needed when using 32GB DIMMS.
I've attached pics of the memory I'm using - any advice much appreciated - I'm running out of ideas