In most computer electronics stores, a customer who comes for RAM slats will be asked first of all where he is going to insert them. It is the area of application that is the main thing that distinguishes DIMM from SODIMM, and technical characteristics are no longer very significant for the average person.
It's easy to figure it out: the form factor of DIMM memory modules is designed for installation in full-size desktop systems, SODIMM is located in laptop cases, office equipment and other compact systems. Both the first and the second type are a printed circuit board with contacts and DRAM memory microchips.
What do we see when we look from a full tower system to a laptop or mini-ITX? A significant difference in size. Naturally, in small cases, the space for components is limited, so they are made as miniature as possible. The main physical difference between DIMMs and SODIMMs is the increased length and, as a result, more contacts.
This is how the RAM DIMM and SODIMM strips look in comparison:
It is immediately noticeable how much shorter modules are designed for compact systems... The form factor is highly regulated, so the length of all DIMMs, regardless of memory type, is 133.35 mm, while SODIMMs are 67.6 mm.
The memory modules must have key slots that block installation in an unsuitable interface, as well as cutouts for attaching the port latches. SODIMM has one of them on each end, they are located 20 mm from the edge with contacts. DIMMs have two, one at a height of 9.5 mm, the other at 17.3 mm (for current DDR3).
DIMMs have more pins: for DDR3 their number is 240 pins versus 204 for SODIMM, for DDR4 - 288 pins and 260 pins, respectively. The rest of the technical characteristics of the RAM strips depend on the specific model: memory timings, operating frequency, capacity can be practically any.
Some time ago, the answer to the question, what is the difference between DIMM and SODIMM, almost necessarily contained an indication of the supply voltage. Indeed, in the past, most compact systems in order to optimize power consumption fed 1.35 V to RAM, while full-size modules required 1.5 V. Today, despite this difference for some models, most DDR3 strips are powered from 1.5 V, regardless of form factor.
|Used for installation in full-size systems||Fits into compact systems, electronics and notebooks|
|Length 133.35 mm||Length 67, 6 mm|
|Two each for mounting on the ends||One slot for mounting|
|240 or 288 pins (DDR3 and DDR4)||204 and 260 pins (DDR3 and DDR4)|