Sony PCG-R505GL - Manual (Page 151)

Upgrading Your Computer’s Memory
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3 Select Sony Notebook Setup from the submenu. The Sony Notebook Setup
dialog box appears.
4 On the About This Computer tab, make sure the System Memory
displayed in the System Information box matches the amount of memory
installed.
The displayed memory may be less than the installed memory due to the
amount used by the display adapter.
Sony Notebook Setup Dialog Box