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Cisco UCS C420 Server Installation and Service Guide
OL-27640-01
Chapter 3 Maintaining the Server
Status LEDs and Buttons
Internal Diagnostic LEDs
The server is equipped with a supercap voltage source that can activate internal component fault LEDs
up to 30 minutes after AC power is removed. The server has internal fault LEDs for fan modules, CPU
sockets, DIMM sockets, the motherboard RTC battery, PCIe sockets, TPM socket, I/O riser socket, and
SD cards.
To use these LEDs to identify a failed component, press the front or rear identification button with AC
power removed (see Figure 3-1 or Figure 3-2 for the identification button location). See Figure 3-3 for
the locations of these internal LEDs.
Figure 3-3 Internal Diagnostic LED Locations
1 Fan module fault LEDs (one on each fan) 5 PCIe card fault LEDs (one for each PCIe
socket on motherboard)
2 CPU fault LEDs on motherboard:
• CPU1 LED = CR69
• CPU2 LED = CR68
• CPU3 LED = CR42
• CPU4 LED = CR43
6 TPM fault LED on motherboard (CR40)
3 DIMM fault LEDs on motherboard (one for
each DIMM socket)
7 I/O riser fault LED on motherboard (CR39)
4 RTC battery fault LED on motherboard 8 SD card fault LEDs on I/O riser
Ta bl e 3 -3 I nte rn al Di agnostic LED States
LED Name State
Internal diagnostic LEDs (all)
• Off—Component is functioning normally.
• Amber—Component has failed.
FAN 1
FAN 2
FAN 3
FAN 4
FAN 5
FAN 6
DIMM L
DIMM M
DIMM G
DIMM H
DIMM K
DIMM J
DIMM F
DIMM E
DIMM R DIMM C
DIMM S DIMM D
PCle 7
PCle 6
PCle 5
PCle 4
PCle 3
PCle 2
PCle 2
DIMM P DIMM B
DIMM N DIMM A
CPU 3 CPU 2
CPU 4 CPU 1
1
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3 3 4
2
2 8
6
7
5
