HP Kayak XU Technical Reference Manual page 51

Installing Two LAN
Remote Power On Cards
From a pure network standpoint, this is supported and both cards will be
functional (for example, from the operating system, it will be possible to have
two LAN cards up and running at the same time).
However, there are restrictions due to the remote manageability boot
features implementation. To support these features, an internal cable is
required between the LAN card and the system board. Only one card can be
attached to this cable, therefore remote manageability features are
supported only on one card.
The problem is that current BIOS and hardware implementation doesn't
allow to identify to which card the cable is attached and this may result in
having none of the remote capabilities working properly. Also, remote boot
can only work on one card.
Therefore, if a customer wants to use two HP LAN cards without using HP
LAN enhanced features (Remote boot, Remote power on), then there is no
problem. However, if there is a requirement to use the HP LAN enhanced
features, then it is not possible, at the present time, to use the two LAN
cards on one system.
Even though it is possible to install two LAN Remote Power On cards in the
computer, only one card is seen by the operating system.
3 Interface Boards and Mass-Storage Drives
10BT/100TX LAN Controller
43