Good Gear Guide
Server walkthrough: Taking apart the HP Proliant D...
The rear of the HP DL380 G6 has four Ethernet ports ('2'), which can also be used for iSCSI; as well, you get PS/2, serial, monitor and USB 2.0 ports ('4'), and an iLO 2 Ethernet port for accessing the server's built-in management console ('3'). There is space for up to six PCI Express expansion cards ('1'); there is an option to have a PCI-X/PCI Express card configuration instead. The UID light on the back ('5') lets you quickly identify the server if you can't get to the front of it.
Server walkthrough: Taking apart the HP Proliant DL380 G6 server