Anatomy of a Motherboard Article

Tidbits Compiled by Marty Sems Graphics & Design by Lori Garris

Anatomy Of A Motherboard he mainboard, or motherboard, is the foundation of a PC. Everything connects to it—the processor, the memory, the storage drives—and the motherboard, in turn, keeps the CPU in communication with all of its subordinate devices. Here are some of the highlights of a current high-end model, MSI’s Big Bang-XPower ($299.99 online; us.msi.com). This board identifies many of its headers (male pin connectors), slots, and other features with silkscreened labels. Some of the abbreviations used are a little cryptic, but the motherboard’s users manual explains most of them. The manual also offers a more thorough diagram of its layout.

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LAN controller. You’ll usually find one or two discrete Gigabit (1Gps; gigabit per second) Ethernet controller chips on a mainboard, one per LAN (local-area network) port.

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PCI-E slots. These fast peripheral slots support PCI-E (Peripheral Component Interconnect Express) version 2.0 and data speeds of up to 8GBps. Long x16 slots (those with 16 PCI-E data lanes; pictured here) can support expansion cards with shorter contact edges and/or slower interfaces such as x8, x4, or x1.

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Battery. This watch-style battery supports BIOS (Basic Input/Output System) settings such as memory timings and the time/date.

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USB headers. These supply power and data to USB 3.0 ports mounted on the front of the case or on rear brackets.

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SATA ports. These ports are for hard drives, SSDs (solid-state drives), and CD/DVD/BD (Blu-ray Disc) drives. The latest SATA (Serial Advanced Technology Attachment) specification supports speeds of up to 6Gbps (gigabits per second).

Fan headers. Case fans can get power here.

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Diagnostics code readout. A few boards present LED (light-emitting diode) status codes to aid in troubleshooting problems. Front panel headers. These pins connect by wire to the power/reset buttons and indicator LEDs on the front of the computer case.

BIOS. This chip stores the Basic Input/Output System that runs the motherboard and its devices at a level underneath the OS (operating system), such as Windows. You can configure processor and memory settings in the BIOS and also enable or disable features of the motherboard. Some enthusiast boards feature a secondary chip with a backup BIOS on it.

Audio codec. This type of compressor/decompressor chip (not shown) turns audio files into faithful 7.1-channel surround sound. Codecs can be integrated onto motherboards or mounted on expansion cards, as in this MSI board’s case.

USB 3.0 controller. Many motherboards feature a secondary SATA and/or eSATA (external SATA) controller chip to add support for more drives.

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Power connectors. The computer’s power supply unit plugs into these jacks, which supply electricity to most devices (aside from drives).

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Rear I/O ports. These video, audio, and data jacks fit into the back panel of a computer case so they’ll be accessible from the rear of the PC. These days, you’ll find ports for USB 3.0, Gigabit Ethernet, 6Gbps eSATA, analog and digital surround sound, perhaps FireWire, and— on motherboards with integrated graphics—DVI (Digital Visual Interface) and HDMI (High-Definition Multimedia Interface).

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Clear CMOS/RTC. This plastic jumper or button lets you return the BIOS to its default settings, which often eliminates erratic behavior. The abbreviations stand for complementary metal-oxide semiconductor, the type of chip holding the BIOS, and the system’s real-time clock.

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CPU socket. This board is compatible with 1,366-pin Intel processors, and its CPU socket has more than a thousand tiny metal springs in it. AMD-compatible sockets have little holes for the processor’s pins.

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Power support components. The processor’s power management circuitry ensures that the CPU is fed the proper voltage in a smooth, reliable fashion. Voltage regulator modules and related components run hot enough to require their own heatsinks.

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DIMM slots. Sticks of RAM fit into these dual in-line memory module slots. This board supports DDR3 (double-data-rate 3) memory. Current processors access the memory directly instead of routing data through the northbridge.

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Chipset. This is a chip or (more often) a pair of chips that manages the data transmissions between the CPU and the rest of the computer’s components. Both are mounted under heatsinks in this example. The current flagship desktop chipset from Intel is known as the X58; AMD’s is the 890FX. The chip closest to the processor is variously called a northbridge, an IOH (input/output hub), and until recently, an MCH (memory controller hub). In current chipsets, it links the CPU to the PCI-E graphics device(s)—which may be integrated with the northbridge—and the southbridge. The southbridge, also known as an ICH (I/O controller hub), communicates with the storage drives, audio codec, Ethernet controller(s), non-graphics PCI-E cards, USB ports, and so on. Southbridges generally incorporate controllers for SATA, IDE (Integrated Drive Electronics), and USB.

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