IBM eServer 240 xSeries User Reference Manual page 64

LEDs for hot-plug PCI slots
Each hot-plug PCI slot has three LEDs associated with it — two Attention LEDs
and one Power LED.
The following table describes the LEDs:
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IBM xSeries User's Reference
Power LED: This LED is on when the hot-plug PCI slot is active and has
power. An adapter must not be added to or removed from the PCI slot when
the Power LED is on. When this LED is off, the PCI slot is inactive and has no
power applied. An adapter can be installed when the Power LED for the PCI
slot is off. Refer to your operating system documentation to determine if it
supports hot-plug PCI adapters, and, if so, how to disable the hot-plug PCI slot.
Attention LEDs: Each hot-plug PCI slot has an Attention LED that is visible
from the rear of the server and one that can be seen from inside the server.
(The LEDs have the same meaning; they are duplicated to be visible from
outside or inside the server.) An Attention LED flashes approximately once per
second when it is on. The meaning of the Attention LEDs is defined by your
operating system. Refer to your operating system documentation to determine
if it supports hot-plug PCI adapters and, if so, what the Attention LEDs indicate.
Power LED Attention LED
On Flashing
On Off
Off Flashing
Off Off
Description
The adapter requires attention. Slot still has
power applied. Do not remove or install an
adapter in the slot. Refer to your operating
system documentation for instructions.
Normal operation; no intervention is required.
The adapter requires intervention. Power is
removed from the slot. An adapter can be
removed or installed in the slot.
Power is removed from the slot. An adapter
can be removed or installed in the slot.