Motherboard
Firmware
- booting
- EFI (Extensible Firmware Interface) supports modern bootloaders
- BIOS (Basic Input Output System)supports legacy bootloaders
- other functions
- identify and test attached hardware
- configure hardware settings
- configure boot settings
- configure security settings
- update firmware
Management
- BMC (Baseboard Management Controller)
- usually found on server motherboards
- permits remote management independent of operating system
- usually includes separate interface for management network
- may include basic (VGA) video
- may include keyboard/mouse over IP
- TPM (Trusted Platform Module)
- manages cryptography outside of the processor
Interfaces
- processor
- specific to generation (may be soldered)
- consult processor support list
- memory
- specific to generation and form factor (may be soldered)
- DDR5 is current, DDR4 still commonly available
- consult memory support list
- storage
- SATA (Serial ATA)
- SAS (Serial Attached SCSI)
- M.2 (NVMe, may support legacy SATA)
- U.2 and U.3 (2.5", NVMe, U.3 also supports SAS)
- may be soldered
- video
- may have HDMI and DisplayPort for processor video
- may have legacy DVI or VGA
- network
- may have RJ45 for built-in ethernet
- may have built-in Wi-Fi and/or Bluetooth
- PCIe expansion
- 1, 4, 8, or 16 lanes
- version 5 (current) 3.92 GT/s per lane
- version 4: 1.96 GB/s per lane
- version 3: 0.98 GB/s per lane
- version 2: 0.5 GB/s per lane
- version 1: 0.25 GB/s per lane
- USB
- USB4 version 2.0: 80 Gbps, power 7.5 W
- USB4 version 1.0: 40 Gbps, power 7.5 W
- USB 3.2 Gen 2x2: 20 Gbps, power 7.5 W
- USB 3.2 Gen 2: 10 Gbps, power 7.5 W
- USB 3.2 Gen 1: 5 Gbps, power 4.5 W
- USB 2.0: 480 Mbps, power 2.5 W
- USB-C connector becoming universal, supports DP video
- USB-PD supports higher power, up to 60 W on A/B connectors, up to 240 W on C connectors
- ATX power input
- 24 pins: +12 V, -12 V, +5 V, +3.3 V, +5 V standby, ground
- 8 pins: +12 V, ground for CPU
- some boards use only +12 V, ground
- on-board voltage regulators supply lower voltages (always for CPU)
- other
- sound
- fans
- legacy I/O (PS/2, serial, parallel)
UNIX considerations
- booting
- EFI generally supported except on the smallest distributions
- BIOS supported on some distributions, the number may be declining
- TPM
- not required, that could change
- interfaces
- established standards are well supported
- new standards may not be supported until open source drivers are completed (usually in months)
- legacy ports are well supported