DDR3 and DDR4 Laptop Memory Compatible? No.

Are DDR3 and DDR4 laptop memory (RAM) compatible? That’s a common question when it comes to memory upgrades. For instance, you bought a new laptop with DDR4 RAM and want to add more memory to it by inserting a DDR3 RAM module from your older laptop. You wonder if that’s possible. Unfortunately, that can’t be done. DDR3 and DDR4 laptop memory are not compatible / interchangeable.

First of all, a DDR3 laptop RAM module can’t physically fit into a DDR4 laptop RAM slot and vice versa. Notches on the connectors of memory sticks are on different places. The same applies to corresponding bumps in the RAM slots on notebook’s motherboards. Also, the number of pins doesn’t match. A DDR3 laptop memory module has 204 pins, whereas DDR4 has 260. Finally, DDR3 memory is a bit shorter than DDR4 – 2.66 versus 2.74 inches.

So, a DDR3 memory module won’t fit in a DDR4 slot…

And a DDR4 stick is incompatible with a DDR3 slot…

Besides the physical differences, DDR3 and DDR4 RAM differ in voltages. DDR3 uses a voltage of 1.5V (or 1.35V for DDR3L variant). DDR4 uses 1.2V. It is more power efficient and generally faster, but doesn’t noticeably improve overall performance nor battery life of notebooks.

Note: If you see “SODIMM” in specs of both DDR3 and DDR4 laptop memory, that doesn’t mean they are compatible. SODIMM only means they are small memory modules commonly used in laptops and some small form factor PCs, as opposed to physically much bigger DIMM memory used in traditional desktop computers. As a side note, DDR3 and DDR4 DIMMs aren’t compatible neither.