Lenovo THINKSERVER 3821 - Manual (Page 92)

3. Remove the server cover and look inside the server for lit LEDs. Certain
components inside the server have LEDs that are lit to indicate the location of a
problem.
The following illustration shows the LEDs on the system board.
1 PCI slot 1 error LED 9 Battery error LED
2 PCI slot 2 error LED 10 System-board error LED
3 PCI slot 3 error LED 11 VRM fail LED
4 HS heartbeat LED 12 CPU 1 error LED
5 PCI slot 4 error LED 13 DIMMs 1 - 8 error LEDs (starting
from the bottom)
6 PCI slot 5 error LED 14 DIMMs 9 - 16 error LEDs (starting
from the bottom)
7 PCI slot 6 error LED 15 CPU 2 error LED
8 IMM heartbeat LED 16 CPU mismatch LED
84 ThinkServer TD200x Types 3719, 3821, 3822, and 3823: Hardware Maintenance Manual