One is a stick you can pull out, the other is a chip you will never see again. Check which one your laptop has before you plan an upgrade.
The short answer
A SO-DIMM (small outline dual in-line memory module) is a compact, replaceable RAM stick for laptops, mini PCs and similar systems. It carries standard DDR chips [1][6]. LPDDR (low power DDR) is a different kind of DRAM chip, designed for mobile devices and power efficiency, and in laptops it is typically soldered onto the board [3][5]. Our assessment: before you buy RAM, find out whether the machine has slots at all, and which standard they use.
How it works
- Two different things. SO-DIMM is a module shape with a socket. LPDDR is a type of memory chip with its own JEDEC standard. JESD209-5C defines LPDDR5 and LPDDR5X as chip devices with packages and ball assignments, with densities from 2 Gb to 32 Gb [2]. So a SO-DIMM holds DDR chips, and an LPDDR laptop has chips on the board.
- SO-DIMM generations. JEDEC lists 260-pin SODIMMs for DDR4 and 262-pin SODIMMs for DDR5 [1]. Different families, so you buy the generation your board supports. The clocked CSODIMM variant fits the same sockets as DDR5 SODIMMs [6].
- Why LPDDR exists. JEDEC designed LPDDR5 and LPDDR5X for mobile uses such as 5G smartphones, and to raise speed and efficiency. The 2021 update extended the speed to 8533 Mbps, up from 6400 Mbps [3].
- The trade-off. As of the December 2023 article, LPDDR5X was available only as soldered chips [5]. Soldering saves space, since thin laptops often have no room for SO-DIMM sockets, but it rules out upgrades and memory repairs later [5][6]. SO-DIMM allows swaps, at the cost of height.
- A third way: CAMM2. JEDEC's JESD318 defines screw-attached modules for DDR5 and for LPDDR5/5X. The two use the same connector design with different pinouts, so they cannot be mounted by mistake [4]. Kingston says that a CAMM2 module can replace soldered LPDDR5 DRAM [6]. Our reading: this makes LPDDR upgradable on laptops that choose it, but you need the matching slot.
A practical example
You look at two mini PCs for a homelab. Machine A lists "2 × SO-DIMM slots, DDR5". Machine B lists "16 GB LPDDR5X, onboard". With A you can start with one stick and add a second later. With B the 16 GB is final, so pick the size you will need in two years. Both are invented examples: our inventory (as of 14 to 16 Oct 2026) records no RAM modules, and we claim no prices.
Checklist
- Read the product data sheet for "onboard", "soldered" or "LPDDR" before you plan an upgrade.
- Identify the generation of the slots (DDR4 260-pin or DDR5 262-pin) [1].
- Compare the maximum capacity and speed in the board manual with the stick you want.
- Choose enough capacity for soldered models, since you cannot add it later [5].
- Look for CAMM2 or LPCAMM2 slots on newer laptops and note that DDR5 and LPDDR5 versions differ [4].
- Test new RAM with a memory test after installing it.