Golden Recursion Inc. logoGolden Recursion Inc. logo
Advanced Search


Dual In-line Memory Module is a form factor of DRAM memory modules

Dual In-line Memory Module (DIMM) is a form factor of DRAM memory modules. This form factor has come to replace the SIMM form factor. The main difference of DIMM from its predecessor is that the contacts located on different sides of the module, are independent, in contrast to SIMM, where the symmetric contacts located on different sides of the module, closed to each other and transmit the same signals. In addition, DIMM implements the function of the detection and correction of errors in 64 (no parity) or 72 (with parity or ECC) data lines, in contrast to SIMM c 32 lines.

Structurally is a memory module in the form of a long rectangular board with a row of pads on both sides along its long side, installed in the connector and fixed at both ends of her snaps. The memory chips can be placed either on one or both sides of the board.

Unlike the SIMM form factor used for asynchronous FPM and EDO memory, the DIMM form factor is designed for SDRAM type memory. Modules designed for 3.3V and (less frequently) 5V supply voltages were produced. However, for the first time in the form factor DIMM appeared modules with memory type FPM, and then and EDO. They were equipped with servers and branded computers.

SO-DIMM module is designed for use in notebooks or as on-board memory expansion, so it has a smaller size.

Later in the DIMM modules was packed memory type DDR, DDR2, DDR3 and DDR4, distinguished by its high-speed performance.

Appearance of DIMM form factor was promoted by the appearance of Pentium processor, which had a 64-bit data bus. In professional workstations, such as SPARCstation, this type of memory has been used since the early 1990s. In general purpose computers, a widespread switch to this type of memory occurred in the late 1990s, around the time of the Pentium II processor.

In the DIMM form factor, memory arrays that implement non-volatile storage, called NVDIMM, can be made. They can be implemented by adding a self-contained power supply and auto-updating functions to DRAM memory (NVDIMM-N) or based on NAND flash memory (NVDIMM-F). Implementations of NVDIMM based on other types of memory (NVDIMM-P) are investigated


There are the following types of DIMM, structurally and electrically incompatible with each other, including SO-DIMM (from small outline, compact modules, used in particular in laptops):

72-pin SO-DIMM (not compatible with 72-pin SIMM) - used for FPM DRAM and EDO DRAM

100-pin DIMM - used for SDRAM

144-pin SO-DIMM - used for SDR SDRAM (sometimes also for EDO RAM) in laptop computers

168-pin DIMM - used for SDR SDRAM (less often for FPM/EDO DRAM in workstations/servers)

172-pin MicroDIMM - used for DDR SDRAM

184-pin DIMM - used for DDR SDRAM

200-pin SO-DIMM - used for DDR SDRAM and DDR2 SDRAM

204-pin SO-DIMM - used for DDR3 SDRAM

214-pin MicroDIMM - used for DDR2 SDRAM and DDR3 SDRAM

240-pin DIMM - used for DDR2 SDRAM, DDR3 SDRAM and FB-DIMM DRAM

260-pin SO-DIMM - used for DDR4 SDRAM

288-pin DIMM - used for DDR4 SDRAM


Further reading


Documentaries, videos and podcasts



Ian Paul
November 4, 2020
How-To Geek
People often draw parallels between computers and the human brain, and sometimes, it's an apt comparison. For example, both the brain and a computer have short- and long-term memory. RAM is where a computer stores its short-term memory.
Steven Walton
January 17, 2020
Today we're taking a look at the performance impact having four DDR4 memory modules can have on performance in a dual-channel system, opposed to just two modules. In this scenario all modules are operating at the same frequency, use the same timings and provide the same total memory capacity.
Golden logo
By using this site, you agree to our Terms & Conditions.