A PCI adapter card that is hosting nonvital system resources can be removed if the device driver supports hot-plugging. A PCI adapter card is not detachable if it is a vital system resource. For a PCI adapter card to be detachable, the following conditions must be met:
The device driver must support hot-plugging.
Critical resources must be accessible through an alternate pathway.
For example, if a system has only one Ethernet card installed in it, the Ethernet card cannot be detached without losing the network connection. This detachment requires additional layered software support to keep the network connection active.