Asus 90SF0091-M00270 User Manual page 82

5. BMC LED (BMCLED1)
The BMC LED lights up to indicate that the on-board BMC is functional.
6. CATT LED (CATTERR1)
The CATT LED indicates that the system has experienced a fatal or catastrophic error
and cannot continue to operate.
4-12 Chapter 4: Motherboard Information