• For servers with eighteen (18) memory slots:

  • There are three (3) channels per processor; six (6) channels per server

  • There are three (3) DIMM slots for each memory channel; eighteen (18) total slots

  • Memory channel 1 consists of the three (3) DIMMs that are closest to the processor

  • Memory channel 3 consists of the three (3) DIMMs that are furthest from the processor

• DIMM slots that are white should be populated first

• Do not mix Unbuffered memory (UDIMMs) with Registered memory (RDIMMs)

• Do not install DIMMs if the corresponding processor is not installed

• If only one processor is installed in a 2CPU system, only half of the DIMM slots are available

• To maximize performance, balance the total memory capacity between all installed processors

• It is not required, but it is recommended to load the channels similarly if possible

• User can only have up to eight (8) ranks installed per channel

• User can only install two quad-rank DIMMs per channel

• User can only install two UDIMMs per channel; if available, the third slot in the channel must remain empty

• Populate DIMMs from heaviest load (quad-rank) to lightest load (single-rank) within a channel

• Heaviest load (DIMM with most ranks) within a channel goes furthest from the chipset

• For memory mirroring mode, channel 3 must be unpopulated. Channels 1 and 2 are populated identically

• For lock-step mode, channel 3 must be unpopulated. DIMMs in channels 1 and 2 will be installed in pairs. The paired slotswill be 1,4; 2,5; 3;6 on a 3DPC system or 1,4; 2,5; on a 2DPC system

• No mixing DIMM voltage; all DIMMs must be the same voltage

• Mixing DIMM speeds is allowed, but the system processor speed rules always override the DIMM capabilities.

• If DIMM speeds are mixed, the memory bus will default to the minimum clock rate of all DIMMs in the system - even if theslower DIMM is on the other processor:

  eg: a) If a 1x 1066 MHz DIMM is installed in channel 1 and 1x 1333 MHz DIMM in channel 2, it will still run at 1066 MHz.

  b) If a 1x 1066 MHz DIMM is installed in channel 1 and 5x 1333 MHz DIMMs with 1 DIMM Per Channel (DPC) in each of the otherchannels, it will run at 1066 MHz.

• If 3DPC is installed in one channel (if applicable) and 1DPC in all other channels, it runs at 800MHz.

• 95 Watt CPU's are required for 1333 MHz DIMM speeds. All other CPU's are capable of up to 1066 MHz.

• References to the above MHz speeds are for the various speeds of DDR3 DIMMs; 1333 refers to DDR3-1333, etc.

Basic memory slot & population diagram

Standard memory configuration (1 CPU model)

Standard memory plus optional memory (1 CPU model)

Standard memory replaced with optional memory (1 CPU model)RDIMM maximum configuration

UDIMM maximum configuration (1 CPU model)

Standard memory replaced with optional memory (2 CPU model)RDIMM maximum configuration

UDIMM maximum configuration (2 CPU model)