A Serial Presence Detect (SPD) refers to a standardized way to be able to access information via PC memory modules. Each JEDEC standard requires certain parameters which are located in the bottom 128 bytes on an EEPROM memory module. These bytes very often include parameters concerning the time, manufacturer, the serial number and other useful information about the memory module and if it had not been programmed correctly it may be the cause for an instable system. Badly programmed SPD EEPROM memory modules are the most common cause for an instable system and very often occur on no-name RAM memory modules.
Here the BIOS also reads out the hardware information. This chip is very well visible on the DIMM memory modules on one of the four corners at the top.
