This stands for Synchronous Dynamic Random Access Memory and is a special type of DRAM that can be found in most new machines. The memory module will normally be a 168-pin DIMM. SDRAM is faster than asynchronous memory because the memory is synchronised with the system bus and clock, and therefore, the processor
Common descriptions of SDRAM include PC66, PC100 and PC133, with the numeric part indicating the memory speed in Mhz.
Common storage sizes of SDRAM memory modules range from 16MB to 2GB and over.
Click on this link to review the wiki resource on SDRAM.
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