Notebook memory was developed as a smaller, more space efficient alternative to the memory used in desktop computers. Because of its smaller footprint it allows laptop computers to host more features for their size.
RAM for desktop computers measures 5.25″ long, and is generally 1.25″ tall. In comparison, laptop memory is about as tall, but measures only 2.66″ across. This halves the amount of space required for memory in the laptop. In addition, while memory in PCs stands upright to aid in airflow across the RAM chips, memory in laptops is angled nearly flat to the board, with one stick partially overlapping the other when both sockets are together. While this increases the heat of the memory and makes it somewhat harder to cool, it also significantly reduces the amount of space needed for the notebook memory.
Physically, there are four different formats of memory for laptops – 100-pin memory, 144-pin memory, 200-pin DDR memory and 200-pin DDR2 memory. Each type fits in a physically different slot, and while the difference between 100-pin, 144-pin and 200-pin memory is pretty easy to see if you look closely, 200-pin DDR and 200-pin DDR2 memory look very similar, and are keyed slightly differently from each other to prevent one type from being installed in the socket for the other type.
The most important feature of 100-pin notebook memory is that it operates with 32-bit data transfer to a 64-bit memory controller in the case of laptops. This means that, unlike 144-pin and 200-pin laptop memory, 100-pin memory requires two modules to be installed at the same time to properly be able to talk to the laptop, or it must work with a 32-bit memory controller. However, 100-pin SO-DIMMs are most commonly used in network printers that might need more memory for large print jobs or large queues of print jobs to be processed, rather then in laptops.
144-pin notebook memory is an older type of memory that uses SDRAM for the most part, although even older Extended Data Out (EDO) and Fast Page Mode (FPM) memory also exists. 144-pin memory can range in size from 32MB to 512MB depending on the type of RAM you are looking at. For most laptop users, PC100 or PC133 memory is what your laptop would use if it uses 144-pin memory.
200-pin laptop memory falls into two categories, depending on what type of memory it uses – DDR and DDR2. Despite having the same number of pins, the two types of memory are keyed differently at the bottom to prevent them from being installed in the incorrect slot. Both DDR and DDR2 memory come in sizes ranging from 128MB up to 2GB of notebook memory in a single module. The most common sizes to purchase these days are 512MB or 1GB modules, depending on your budget and your needs for your laptop.
DDR Memory comes in three different common speeds – 266MHz, 333MHz and 400MHz. While laptops that use 266MHz memory are growing more uncommon these days, both 333MHz and 400MHz memory in laptops is still very common to come across. If you’re unsure what speed of memory your laptop has in it and cannot determine it, purchasing DDR400 memory is the best course. Either it is the correct speed for your laptop, or the new DDR400 notebook memory will slow down to DDR333 speeds if that is what is installed in your laptop.
DDR2 memory comes in a number of speeds as well – 400MHz, 533MHz and 667MHz. Like DDR memory, it is generally safe to mix speeds of DDR2 memory if you cannot determine the appropriate speed of the memory in your laptop, and thus purchasing DDR2-533 or DDR2-667 is probably the best course to avoid accidentally slowing down the memory of your laptop by adding slower memory. You should determine if you have DDR or DDR2 memory however, before looking to purchase either type, since as said above, DDR and DDR2 memory will not work together because they are physically incompatible.
Finally, notebook memory also exists for Apple laptops. Like PC laptops, Apple laptops take the same types of memory in the same formats, but unlike PC laptops, Apple computers have much less tolerance for memory that is of the incorrect speed or make. For example, a PC can have memory of two different speeds, such as DDR333 and DDR400 installed, and the faster memory will slow down to work with the slower memory. However, Apple computers will generally not do this, but expect to have only one speed of memory installed. Because of this, it is very important to know exactly what type of notebook memory your Apple laptop needs so that the computer works correctly with the RAM you install in it.
If you have your laptop’s manual, it might say what type of memory you need, but rather then dig out your manual, we have an easier solution for you. If you’re surfing our website on your laptop, click the ‘Check Your Computer’ button below, and it will report what type of memory your computer can use, as well as how many RAM sockets your computer has and how much memory it can use in total. If you’re surfing on another computer and know your laptop’s model number, enter it in the model number field and you’ll be taken to a page that gives information on that model of laptop, such as it’s standard RAM, number of slots, and the RAM it takes. Both pages will also include a selection of RAM upgrade options to give you an idea of what you can upgrade your laptop with and what the prices are to upgrade.
Otherwise, feel free to take a look at your memory options on the left-hand side, where you can find many different kinds of desktop and notebook memory, as well as memory cards for PDAs, cameras, cellphones and more.