03-12-2014 04:47 PM
I want to upgrade an HP Z400 workstation with 4 DIMM slots. It now has 3 HMT125U7BFR8C-H9 modules, giving 6 GB. This is a triple channel system, with two channels with one slot, and one channel with two slots. This image shows the memory architecture.
I believe that the best strategy would be to replace the three 2 GB DIMMs I have now with a matched set of three 4 GB DIMMs. However, the Crucial page which shows supported products for the Z400 with 4 DIMM slots only lists sets of two DIMMs. Who is right? Is it best to use sets of two or sets of three DIMMs?
The page for the Z400 with 6 DIMM slots lists sets of 3. Should I get one of those instead, and can I safely assume they are compatible with the Z400 with 4 DIMM slots?
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03-14-2014 03:05 PM
Thanks for contacting us today. I pulled up your system and it doesn't appear that it runs in triple channel or even dual channel. From the user manual on HP's site it appears that it can handle any variety of memory. This can be found on PG. 13 here. However, the memory for the two systems is completely identical. If you feel more comfortable ordering a kit of three memory modules you may. Please let us know if you have any other questions or concerns.
03-14-2014 05:46 PM
It is true that the workstation will function with various memory arrangements, but with the right arrangement it can function in triple channel mode and give better performance. The HP Z400 Memory Configuration and Optimization document shows how certain configurations are better in the version with 4 slots. Another HP Z400 Workstation Memory configuration and optimization (June 2010) document tells about triple channel and shows how arrangements in 6 slot workstations.
03-17-2014 03:21 PM - edited 03-17-2014 03:23 PM
Thank you for the extra information. Because the memory is the same for both the 4 slot or 6 DIMM model, I would recommend going with the kit displayed on the 6 DIMM page. Please let us know if there is anything else we can help you with.