if both banks have 2 GB RAM modules then it should be set as dual-channel. I don’t know of any Linux tool that will tell you if it’s dual or not. On my machines, during POST, the BIOS reports if my RAM is running as dual or not
Dual-channel is a hardware specific option; the operating system has little bearing control on this. Nearly all laptops that support 4GBs of RAM probably have dual-channel capabilites.
Many times there will be an option at the laptop boot logo to view more information by pressing a button (eg. tab, esc).
I would also look in the BIOS for a system information option; this would probably say if you were running dual-channel or not.
Alternatively, if you look in the BIOS for a setting such as “Display logo”, disable/enabling this option would allow you to view the system information as the laptop goes through POST. This is where it would tell you if you’re running dual-channel or not.
Just a comment to somebody who can’t enter the BIOS setup of his thinkpad and stumbles upon this thread.
Upon pressing the blue thinkvantage button during boot a timer should show up, and you may press F1 to enter setup. If you are in diagnostic mode, and see only random pixels instead of a timer, F1 still works. (At least it worked for me.)
Thanks again to all who helped me with my question.