Your IBM PC AT can support up to N/A of memory. For optimal system performance install the maximum amount of memory in each memory socket, this system comes with standard amount of   N/A RAM. One or more of the sockets in the system might be already filled with memory. Whenever you upgrade, you can either add memory to one of the open sockets and/or remove memory from a filled socket and replace it with a higher capacity memory module. Select your Memory Upgrade for IBM PC AT.