4 GB Installed 2.75 GB Usable

This motherboard had a problem where the BIOS would not recognise all the memory installed. According to the manufacturer manual, each memory slot can accept a maximum of 1GB, but the BIOS was showing only 2.75 GB. Some useless blogs mentioned how it could be due to bent pins in the processor socket, so I removed the processor and took a photograph to check each pin. As you can see, there was nothing wrong with the socket pins.

In the end, the problem was solved when I replaced the memory modules with double-sided ones (2R×8). Double rank modules usually have 512 MB capacity on each side of the module making up 1 GB. Since the address space for each module can access only 512 MB at any one time, the motherboard is able to access the full 1 MB on the module using control lines to choose the rank (side).

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