Unbuffered DIMMs (UDIMMs)

The following notes provide information that you must consider when you install UDIMMs:

The memory channels run at the lowest common frequency of the DIMMs installed.
The UDIMM options that are available for the server are 1 GB, 2 GB, 4 GB, and 8 GB (when available) DIMMs.
The server supports up to two single-rank or dual-rank UDIMMs per channel.

The following table lists the supported UDIMM population.

Table 1. Supported UDIMM population per channel.
Five column table for documenting the DIMM connectors per channel, DIMMs installed in each channel, DIMM type, DIMM speed, and ranks per DIMM (any combination).
DIMM connectors per channel	DIMMs installed in each channel	DIMM type	DIMM speed	Ranks per DIMM (any combination)
2	1	Unbuffered DDR3 ECC	1333, 1600	Single-rank, dual-rank
2	2	Unbuffered DDR3 ECC	1333, 1600	Single-rank, dual-rank

The following table lists the maximum DIMM population using ranked UDIMMs.

Table 2. Maximum memory population using ranked UDIMMs (depending on your model).
Four column table for documenting the number of UDIMMs, DIMM type, size, and total memory.
Number of UDIMMs	DIMM type	Size	Total memory
4	Single-rank UDIMMs	1 GB	4 GB
4	Dual-rank UDIMMs	2 GB	8 GB
4	Dual-rank UDIMMs	4 GB	16 GB
4	Dual-rank UDIMMs	8 GB (when available)	32 GB

The following table shows the UDIMM memory population rule to optimize the system performance.

Table 3. UDIMM population rule.
Four column table for documenting the DIMM connector 1, DIMM connector 2, DIMM connector 3, and DIMM connector 4.
DIMM connector 1	DIMM connector 2	DIMM connector 3	DIMM connector 4
Populated	Empty	Empty	Empty
Populated	Empty	Populated	Empty
Populated	Populated	Populated	Populated

The following illustration shows the location of the DIMM connectors on the system board.

Note

The illustrations in this document might differ slightly from your model.

Figure 1. DIMM connectors on system board

Attention

Static electricity that is released to internal server components when the server is powered on might cause the server to halt, which might result in the loss of data. To avoid this potential problem, always use an electrostatic-discharge wrist strap or other grounding system when you work inside the server with the power on.

To install a DIMM on 4U server models with non-hot-swap power supplies, complete the following steps. For the 5U server model with hot-swap power supplies, please see the next sub-section.

Read the safety information in Safety and Installation guidelines.

Locate the DIMM connectors on the system board. Determine the connectors into which you will install the DIMMs. Install the DIMMs in the sequence shown in the following table.

Table 4. DIMM installation sequence.
Two column table for documenting the number of DIMMs and installation sequence (connectors).
Number of DIMMs	Installation sequence (connectors)
First pair of DIMMs	1, 3
Second pair of DIMMs	2, 4

Open the retaining clips and, if necessary, remove any existing DIMM.
Attention
To avoid breaking the retaining clips or damaging the DIMM connectors, open and close the clips gently.
Figure 2. DIMM installation
Touch the static-protective package that contains the DIMM to any unpainted metal surface on the outside of the server. Then, remove the DIMM from the package.
Turn the DIMM so that the DIMM keys align correctly with the connector.
Insert the DIMM into the connector by aligning the edges of the DIMM with the slots at the ends of the DIMM connector.
Firmly press the DIMM straight down into the connector by applying pressure on both ends of the DIMM simultaneously. The retaining clips snap into the locked position when the DIMM is firmly seated in the connector.
Note
If there is a gap between the DIMM and the retaining clips, the DIMM has not been correctly inserted; open the retaining clips, remove the DIMM, and then reinsert it.
Install the air baffle (see Replacing the air baffle).
Install the side cover (see Replacing the side cover).
Stand the server back up in its vertical position.
Install the bezel (see Replacing the bezel).
Reconnect the external cables and power cords; then, turn on the attached devices and turn on the server.

To install a DIMM on the 5U server model with hot-swap power supplies, complete the following steps. For 4U server models with non-hot-swap power supplies, please see the above sub-section.

Read the safety information in Safety and Installation guidelines.

Locate the DIMM connectors on the system board. Determine the connectors into which you will install the DIMMs. Install the DIMMs in the sequence shown in the following table.

Table 5. DIMM installation sequence.
Two column table for documenting the number of DIMMs and installation sequence (connectors).
Number of DIMMs	Installation sequence (connectors)
First pair of DIMMs	1, 3
Second pair of DIMMs	2, 4

Open the retaining clips and, if necessary, remove any existing DIMM.
Attention
To avoid breaking the retaining clips or damaging the DIMM connectors, open and close the clips gently.
Figure 3. DIMM installation
Touch the static-protective package that contains the DIMM to any unpainted metal surface on the server. Then, remove the new DIMM from the package.
Turn the DIMM so that the DIMM keys align correctly with the connector.
Insert the DIMM into the connector by aligning the edges of the DIMM with the slots at the ends of the DIMM connector. Firmly press the DIMM straight down into the connector by applying pressure on both ends of the DIMM simultaneously. The retaining clips snap into the locked position when the DIMM is firmly seated in the connector. If there is a gap between the DIMM and the retaining clips, the DIMM has not been correctly installed. Open the retaining clips, remove the DIMM, and then reinsert it.
Stand the server back up in its vertical position.
Install and lock the side cover (see Replacing the side cover).
Reconnect the external cables and power cords; then, turn on the attached devices and turn on the server.

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