Asus TS500-E8-PS4 User Manual page 75

3. CPU Warning LED (ERR_CPU1, ERR_CPU2)
The CPU warning LEDs light up to indicate failure on either CPU1, CPU2, or both.
4. CATT LED (CATTERR_LED1)
The CATT LED indicates that the system has experienced a fatal or catastrophic error
and cannot continue to operate.
ASUS TS500-E8-PS4
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