Sun Microsystems Sun Ultra 60 Service Manual page 188

Figure C–3 Memory System Functional Block Diagram
As shown in Figure C–4, the memory module is arranged in four banks. DIMMs are
always accessed four at a time. Consequently, the DIMMs must be installed in
groups of four (quad) and individual DIMMs within a bank must be of equal
capacity. Figure C–5 illustrates DIMM row mapping.
Caution - Failure to populate a DIMM bank with DIMMs of equal capacity will
result in inefficient use of memory resource or system failure.
Note - For best system performance, install four identical DIMMs.
Sun Ultra 60 Service Manual ♦ March 1999, Revision A
C-8