HPE ProLiant memory population rules: how to add RAM correctly

Adding memory to an HPE ProLiant server is simple mechanically, but the result depends on following the population rules: which DIMMs the processors accept, which ones can be mixed, and which slots to fill first. Those rules are specific to each model and processor family, so this guide gives the general rules HPE publishes, shows where to find the exact rules for your server, and explains how to confirm the upgrade in iLO afterwards.

Step 1 — Record what is installed now

1. In iLO 5 or iLO 6, click System Information and then the Memory tab.
2. Check Memory Summary (total memory and operating frequency) and Advanced Memory Protection (the active mode).
3. In Physical Memory, click show empty memory slots to see free slots, and select a module to see its details.

Health data on this page is current only after the server has been powered on and POST has completed.

Step 2 — Check compatibility with the processor

The installed processor decides which DIMM type the server accepts. Examples from HPE documentation:

HPE's compatibility rules:

• Functional compatibility means the same size, speed and configuration. Two modules with the same HPE spare part number are compatible.
• Within the same memory bank, spare part numbers must be the same.
• On the DL380 Gen10 Plus, mixing LRDIMM and RDIMM is not supported, and mixing 3DS and non-3DS memory is not supported.
• On the DL380 Gen11, mixing x4 and x8 memory is not allowed, 3DS and non-3DS cannot be mixed, and 96 GB DIMMs cannot be mixed with any other memory.

These are examples. Check the memory matrix page for your model: AMD EPYC models and other DL/ML models have their own lists.

Step 3 — Plan the slot population

HPE's general population rules (Gen10 Plus memory matrix):

• Install DIMMs only if the corresponding processor is installed. With one processor in a two-processor server, only half of the DIMM slots are available.
• Balance the total memory capacity between all installed processors for best performance.
• White DIMM slots mark the first slot to populate in a channel.
• Maximum memory speed depends on memory type, memory configuration and processor model.

Speed also changes with DIMMs per channel. For example, the DL380 Gen11 matrix states that 4800 MT/s DIMMs run at 4800 MT/s with one DIMM per channel and 4400 MT/s with two DIMMs per channel. Slot numbering also differs: slots are numbered 1 to 12 per processor on the DL380 Gen10 and 1 to 16 per processor on the DL380 Gen11. Take the exact slot order for your DIMM count from HPE's population rules document for your processor family.

Step 4 — Install the DIMMs

The DL380 Gen11 user guide procedure (other models are similar; follow your model's guide):

1. Power down the server and disconnect every power cord from the power source and from the server.
2. Extend or remove the server from the rack and remove the access panel.
3. Remove the air baffle.
4. Open the DIMM slot latches and install the DIMM. With max-performance heatsinks, position the DIMM under the heatsink wing.
5. Install the air baffle and access panel, return the server to the rack, reconnect power and power up.

Step 5 — Choose the Advanced Memory Protection mode

Open System Utilities (F9) > System Configuration > BIOS/Platform Configuration (RBSU) > Memory Options > Advanced Memory Protection. Options documented for Gen11:

• Advanced ECC Support: largest memory capacity for the OS; protects against all single-bit failures and some multi-bit failures.
• HPE Fast Fault Tolerant (ADDDC): keeps running through multiple DRAM device failures on a DIMM. Needs at least two ranks on each populated channel and HPE SmartMemory in x4 organization.
• Mirrored Memory with Advanced ECC Support: maximum protection, but you must install additional memory.

The Gen10/Gen10 Plus guide also lists Online Spare with Advanced ECC Support, and states Advanced ECC is required when NVDIMMs are installed. The DL380 Gen11 matrix notes that if Memory Fault Tolerance is selected, only x4 memory options can be selected.

Step 6 — Verify the upgrade

1. Let the server complete POST, then open the iLO Memory tab again.
2. Every new module should show Good, In Use. Statuses such as Map Out Configuration, Does Not Match, Not Supported or Configuration Error point to a population or compatibility problem.
3. Confirm total memory, operating frequency and the AMP mode status.
4. Check the Integrated Management Log. For example, on Gen11 the message "DIMM Initialization Error - Processor %1 Channel %2" means a channel could not be trained and was mapped out; HPE's action is to reseat the DIMMs in that channel and update the System ROM.

For persistent errors after an upgrade, see correctable and uncorrectable memory errors.

Frequently asked questions

Why does the memory run slower than the speed on the DIMM label?

HPE states that maximum memory speed is a function of memory type, configuration and processor model. Populating two DIMMs per channel can lower the speed, as in the DL380 Gen11 example above.

Can I use DIMMs from another vendor or another HPE kit?

HPE defines compatibility by its qualification process: modules with the same HPE spare part number are compatible, and part numbers must match within a memory bank. Use the memory matrix for your model.

Checklist

• Model, processor generation and current DIMMs recorded from iLO.
• New DIMMs match the processor's supported type and the model's mixing rules.
• Slot order taken from HPE's population rules for your model and processor.
• Capacity balanced across processors.
• AMP mode chosen and its requirements met.
• All DIMMs show Good, In Use; IML has no new memory errors.

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