quad-rank DIMMs in the sockets with white release tabs and dual-rank DIMMs in the sockets withblack release tabs.• In a dual- or four-processor configuration, the memory configuration for each processor must beidentical. For example, if you populate socket A1 for processor 1, then you must populate socket B1for processor 2, and so on.• Memory modules of different sizes can be mixed provided that other memory population rules arefollowed (for example, 8 GB and 16 GB memory modules can be mixed).• Populate four DIMMs per processor (one DIMM per channel) at a time to maximize performance.• If memory modules with different speeds are installed, they operate at the speed of the slowestinstalled memory module(s) or slower depending on system DIMM configuration.• Populate DIMMs based on the following processor-heat sink configurations.Table 1. Heat sink — processor configurationsProcessorconfiguration Processor type (inWatts) HeatsinkwidthNumber of DIMMsMaximum systemcapacity Reliability, Availability,and Serviceability (RAS)featuresDual processor Up to 105 W, 120 W,or 135 W74mm24 24Quad processor Up to 105 W, 120 W,or 135 W74mm48 48NOTE: If you are using a 1.8 inch hard drive/SSD system with four processors,ensure that you use only 74 mm wide heat sinks for processors up to 105 W,120 W, or 135 W.Up to 120 W or 135 W 94mm40 (Three DIMMs inchannel 0 and channel2 and two DIMMs inchannel 1 and channel3)32 (Two DIMMs perchannel)NOTE: If you are using a 2.5 inch hard drive/SSD system with four processors,ensure that you use only 94 mm wide heat sinks for processors up to 120 W or135 W.Mode-specific guidelinesFour memory channels are allocated to each processor. The possible configurations depend on thememory mode selected.NOTE: x4 and x8 DRAM based DIMMs can be mixed providing support for RAS features. However,all guidelines for specific RAS features must be followed. x4 DRAM based DIMMs retain SingleDevice Data Correction (SDDC) in memory optimized (independent channel) mode. x8 DRAM basedDIMMs require Advanced ECC mode to gain SDDC.The following sections provide additional slot population guidelines for each mode.50
