Jim on Engineering | More on the motherboard

On this episode of Jim on Engineering, Jim Shaw, Alan High, Will Byers, and Mike Steffen further discuss the PCH, BMC, TPM, and many other chips on the motherboard.

Platform Controller Hub (PCH)

  • Connects to CPU via high-speed interface
  • Low speed interfaces:
    • USB 2.0
    • LPC or eSPI
    • GPIO
    • SATA or SAS connectivity
  • PCIe Switch
  • Interface to BMC
  • Intel Management Engine
    • Tiny BMC
  • Power management



Baseboard Management Controller (BMC)

  • Small, specialized processor used for remote monitoring and management of a host system
  • Interface to:
    • Intelligent Platform Management Interface (IPMI)
    • PCIe bus
    • Video output – Facilitates remote access
    • Serial ports – Allows console redirection
    • Monitoring
      • CPU temperatures
      • Memory temperature
      • Fan speeds (can be a fan controller)
      • Voltages
      • PM (Power Management) Bus
      • SM (System Management) Bus

Trusted Platform Module (TPM)

  • An integrated circuit (microcontroller) that can securely store artifacts used to authenticate the platform (your PC or laptop).
  • Artifacts could be:
    • Passwords
    • Certificates
    • Encryption Keys
    • Firmware checksums
  • Hardware root of trust
  • Some possible features:
    • Tamper resistant enclave
    • Secure boot measurement
  • It’s the vault!


  • Network Interface Controller (NIC)
  • Memory
    • ECC, registered, buffered
    • DDR types