3Com’s Fast EtherLink XL (10/100) documentation suggests that you place the 3C905B card into PCI Slot 1 or Slot 2 to allow improved performance. This is due to PCI Slot 1 and 2 having a feature called „PCI Bus Mastering“ which 3Com’s hardware takes advantage of.
However, attempting to use either of these first two slots, coupled with use of BeOS’s 3Com Fast EtherLink XL (3C900/3C905) driver, results in the (Layer 2) ethernet driver being able to see the card, but not be able to transmit or receive from the UTP cable. (Layer 1!)
Moving the 3C905B card to PCI Slot 3 or 4 remedies this situation and allows proper functionality of the card.
I currently have 2 Intel PII BeBoxen linked via CAT 5 cross-over UTP at full duplex 100 Megabit communication. And yes, it’s blazingly fast. One of the boxes also has another PCI NE2000 card hooked up to Cable Modem/ADSL, and both machines can comunicate to the Internet via Richard Burgess‘ NAT software plug-in .