Ubuntu – Why does Ubuntu only show 3GB of RAM

ram

I have an Asus G50vt-x5 laptop with 4GB of RAM installed. But Ubuntu 10.10 shows only 3GB of RAM. Why is it only showing 3GB of RAM instead of the full 4GB?
output of free command is :

neal@ubuntu:~$ free
             total       used       free     shared    buffers     cached
Mem:       3095668    2972784     122884          0     747996    1590044
-/+ buffers/cache:     634744    2460924
Swap:            0          0          0

Best Answer

If you installed the 32-bit version of Ubuntu, it won't recognize over 4GB of memory. You will need to install the 64-bit version of Ubuntu for the system to recognize more than 4GB of memory.

See also:

Note that the standard now is for the Ubuntu images to build and ship with the PAE enabled kernel which allows the use of more than 4GB RAM on 32-bit systems. However, this requires the use of a PAE-capable processor in your system. If your system is sufficiently old, the PAE kernels will not work, and the above restriction of a 4GB memory limit will still stand.

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