Here are some of the original Driver CDs for the D875PBZ.
https://archive.org/search.php?query=D875PBZ
This model uses the Intel CSA bus for the network card. Perhaps, for correct operation, you need the original driver for this board, supplied on the official Driver CD.
Previously, you could download updated driver versions for this model on the Intel website. At a minimum, their names can be found via web.archive.org from around 2003-2005.