Installing Memory (DIMMs)

This chapter explains how to correctly install and populate memory modules (DIMMs). Following these guidelines is essential for system stability and to get the best performance from your server.

Memory support and population rules

To ensure your server runs optimally, you must use supported memory types and install DIMMs in a specific order.

Supported Memory Types

Processor	Memory Type	Max Speed (1DPC / 2DPC)	Max Capacity per DIMM	Supported Configurations
Intel Xeon Scalable Gen 6	DDR5 RDIMM	6400 MT/s / 5200 MT/s	256 GB	8-channel, 1DPC or 2DPC

Memory Population Guidelines

Configuration	Installed CPUs	Total DIMM Slots	Max DIMMs Supported	Population Rule	Performance Note
Minimal (1DPC)	1 (CPU0 only)	8 (CPU0 side)	8	Populate slots A1, B1, C1, D1...	Enables max memory speed (e.g., 6400)
Balanced (2DPC)	1	8	16 (with dual-rank DIMMs)	Fill all 8 slots evenly	Slight speed reduction expected
Dual CPU, 1DPC	2	16	16	Use A1–H1 (CPU0), A1–H1 (CPU1)	Maintains interleaving & bandwidth
Dual CPU, 2DPC	2	16	32 (if supported)	Fill A1–H2 (CPU0), A1–H2 (CPU1)	Speed may drop (e.g., from 6400→5200)

Common Mistake: Mixing memory Modules

Never mix different types of memory (e.g., RDIMMs and LRDIMMs) or DIMMs with different speeds or capacities in the same system. This can cause boot failures, unpredictable errors, or force all memory to run at the speed of the slowest module.

Installing a DIMM

Before you begin, make sure you are properly grounded using an ESD wrist strap.

To install a DIMM:

1. Locate the correct DIMM slot. Identify the slot you will populate based on the population rules.

2. Open the ejector clips. Gently press outward on the white or blue ejector clips on both ends of the slot to open them.

3. Align the DIMM with the slot. Hold the memory module by its edges. Align the notch on the bottom edge of the DIMM with the key in the DIMM slot.

4. Insert the DIMM. Press down firmly and evenly on both ends of the DIMM until it is fully seated in the slot. The ejector clips will automatically swing inward and lock the DIMM in place.

Removing a DIMM

To remove a DIMM:

1. Simultaneously press both ejector clips outward to release the DIMM from the slot.

2. Gently lift the DIMM straight up and out of the slot.

3. Immediately place the removed DIMM into an anti-static bag.