6 GB of RAM but just 4 working

[Tom H]

>>> I put in the 4 GB new RAM and have the old 2GB in as well but
>>> for some reason Lucid only says 4 GB on top. I know the old
>>> one might be slower than the new, but not sure that would
>>> cause it to not be seen.

>> Some boards can only access 4GB (or less depending on age). Check the spec.

> Dont you have to install the server version to access more ram?

> http://www.cyberciti.biz/faq/ubuntu-linux-4gb-ram-limitation-solution/

You have to install a "Server"/PAE kernel if you are using a 32-bit
kernel but Karl has said that he is using a 64-bit kernel.