Understanding DDR Serial Presence Detect (SPD) Table. Monday, July 14, 2003 Understanding DDR Serial Presence Detect (SPD) Table By: DocMemory Serial Presence Detect (SPD) data is probably the most misunderstood subject in the memory module industry.
SDRAM DIMM (168 pin, Unbuffered) pinout and wiring. DIMM. Two types of DIMMs: a 168-pin SDRAM module (top) and a 184-pin DDR SDRAM module (bottom).
Note that the SDRAM module has two notches on the bottom edge, while the DDR1 SDRAM module has only one. Also note that both modules have 8 RAM chips, but the lower one has an unoccupied space for a 9th.