The component in question is a DS1204 security key. Driver software can
access this key to uniquely determine information about the board.
Earlier versions of the PCII/PCIIA were be implemented with generic
parts available from several vendors. This allowed boards to be cloned
and allowed one company's driver software to be used with another
company's hardware. Some companies only developed a board and told
customers to use another companies driver software. The addition of a
DS1204 security key allowed a driver to determine if a particular board
was made by that company. It also allowed OEMs to write their own
driver software and control on which boards it would run.
I'm not too familiar with the inner workings of the DS1204. The
interface to the DS1204 was carried forward into the TNT4882. You can
read about the interface and access methods to a DS1204 in the TNT4882
manual.
If you have one board with this component and one board without it, I
am guessing you bought the board with the component from someone other
than NI. The presence of this component should not limit the function
of the board.