Cisco Systems UCS C420 manual Socket Color, Black

Chapter 3 Maintaining the Server

Installing or Replacing Server Components

DIMM Population Rules

Observe the following guidelines when installing or replacing DIMMs (see Figure 3-13):

•The minimum configuration is one DIMM installed in any of CPU1’s blue sockets (A1, B1, C1, D1).

•When populating a channel, fill the blue socket first, and then fill the black sockets (1, 2, 3).

•The server supports one, two, or three DIMMs per channel for single- or dual-rank DIMMs.

•The server supports only one or two quad-rank registered DIMMs (RDIMMs) per channel. The server supports one, two, or three quad-rank load-reduced DIMMs (LRDIMMs) per channel.

•The server supports RDIMMs or LRDIMMs. Do not mix RDIMMs and LRDIMMs in a server.

•Unregistered DIMMs (UDIMMs) and non-ECC DIMMs are not supported.

•For memory mirroring population rules, see Memory Mirroring Mode, page 3-25.

•There is no requirement to install DIMMs evenly across all CPUs. However, for optimal performance, you should populate sockets in the order that is shown in Table 3-4for two-CPU systems or Table 3-5for four-CPU systems.

		Table 3-4	DIMM Population for Two-CPU System Optimum Performance
		# of DIMMs		DIMM
		Installed	CPU	Socket	Color
		First: 1	CPU1	C1	Blue
2			CPU2	E1	Blue
3			CPU1	D1	Blue
4			CPU2	F1	Blue
5			CPU1	B1	Blue
6			CPU2	H1	Blue
7			CPU1	A1	Blue
8			CPU2	G1	Blue
9			CPU1	C2	Black
10			CPU2	E2	Black
11			CPU1	D2	Black
12			CPU2	F2	Black
13			CPU1	B2	Black
14			CPU2	H2	Black
15			CPU1	A2	Black
16			CPU2	G2	Black
17			CPU1	C3	Black
18			CPU2	E3	Black
19			CPU1	D3	Black
20			CPU2	F3	Black
21			CPU1	B3	Black
22			CPU2	H3	Black
23			CPU1	A3	Black
		Last: 24	CPU2	G3	Black
					Cisco UCS C420 Server Installation and Service Guide
	OL-27640-01					3-23