There are two important features to look for when upgrading the memory: what will your hardware support and operating system limitations. With regard to operating system limitations, Windows and Mac 32-bit operating systems will not support more than approximately 3 gigabytes of memory. Linux 32-bit will support more than 3 gigabytes of memory, but requires recompiling the kernel.
For Windows and Mac operating systems, it is a limitation of the operating system and can only be overcome by changing to a 64-bit operating system. Windows XP uses a 32-bit operating system, with very few exceptions. (Reference: http://windows.microsoft.com/en-us/windows7/32-bit-and-64-bit-Windows-frequently-asked-questions) Windows Vista and Windows 7 can be either 32-bit or 64-bit. Mac OSX 10.5 (Leopard) and above are 64-bit operating systems but earlier versions are 32-bit.
To determine if Windows Vista or Windows 7 is 32-bit or 64-bit:
- Left-click the Start button.
- Right-click Computer.
- Left-click Properties. The System Properties are displayed and will show the version of the operating system.
Once you know what your operating system is the next step is to determine what your hardware will support. There are different ways to do this:
- If you know the manufacturer and model of the computer or motherboard, you can look the information up on the manufacturer’s web site. The information is typically in the technical specifications for that model. Below is an example of the information from Hewlett Packard’s web site:
Note that it shows the memory that came installed on the computer and the type of RAM that is compatible (in this case PC3-8500 and PC3-10600), how many slots are available, and that it is Dual channel. Dual channel memory should be matched for best performance, although it is not required for the computer to operate.
- An alternative to the manufacture site or user’s manual is to use a system scanning utility. An example of this is the Crucial memory scan utility available at www.crucial.com. Below is an example of the output from using the Crucial utility: