Dell Precision T5500 (Early 2009) - Manual (Page 3)

Memory Subsystem
The memory subsystem consists of three DDR3 memory channels attached to each processor. All single-processor configurations have six DIMM slots (two per
channel) attached to the primary processor located on the system board. Dual-processor configurations require an optional riser card that contains the
secondary processor and the DIMMs associated with the secondary processor. There are six DIMM slots on the riser, for a total of twelve DIMMs in the system.
Memory Slots
There are six memory slots on the system board. The slots are numbered DIMM1 through DIMM6. DIMM1 is furthest from the processor.
In addition, the dual-processor riser features three additional memory slots. The slots are numbered DIMM1 through DIMM3. DIMM1 is furthest from the
processor.
72 DR 8 GB 8 GB 8 GB 8 GB 8 GB 8 GB 8 GB 8 GB 8 GB
NOTE: If more than one Quad rank DIMM is installed within a channel (DIMM1 & DIMM4, DIMM2 & DIMM5, DIMM3 & DIMM6) then the maximum DDR3
speed is reduced to 800 MHz. Spreading Quad Rank memory modules across multiple channels is recommended.
NOTE: DDR3 DIMMs have 240 pins, the same number as DDR2, and are the same size, but are electrically incompatible and have a different key notch
location.
DIMM slot configuration for a single processor or a second processor on the riser.