di seguito copio e incollo cosa riporta il manuale d'uso ibm 300pl .......
Ethernet Setup
If your model has an integrated Ethernet controller, you
can use the Ethernet Setup menu to enable or disable the
Ethernet feature and view or change related settings.
Notes:
1. If your model has an integrated Ethernet controller
and you install an optional network adapter, you must
disable Ethernet support.
2. If your model does not have an integrated Ethernet
controller but has an optional network adapter, you do
not have the option of selecting RPL or DHCP. Also,
you do not have the viewable MAC address feature.
e quindi sembra che se nella bios disabiliti la scheda di rete "ethernet support" disabiliti quella integrata