Asus RS700-X7/PS4 - Manual (Page 56)

Chapter 4: Motherboard information 4-14
10. Serial port connectors (10-1 pin COM1/COM2)
These connectors are for the serial (COM) ports. Connect the serial port
module cable to one of these connectors, then install the module to a slot
opening at the back of the system chassis.
11. TPM connector (20-1 pin TPM1)
This connector supports a Trusted Platform Module (TPM) system, which can
securely store keys, digital certificates, passwords, and data. A TPM system
also helps enhance network security, protects digital identities, and ensures
platform integrity.
Only COM1 functions when BMC is Enabled.