Motherboard

Alternatively referred to as the mb, mainboard, base board, main circuit board, system board, or a logic board.The motherboard is a printed circuit board that is the foundation of a computer. It allocates power to the CPU, RAM, and all other computer hardware components. Most importantly, the motherboard allows hardware components to communicate with one another.The first motherboard is considered to be one used in the IBM Personal Computer, released in 1981. Below is a picture of the ASUS P5AD2-E motherboard with names of each major component of the motherboard.

Expansion Slot

Alternatively referred to as a bus slot or expansion port, an expansion slot is connection or port located inside a computer on the motherboard or riser board that allows a computer hardware expansion card to be connected. For example, if you wanted to install a new video card in the computer, you'd purchase a video expansion card and install that card into the compatible expansion slot.

Computer expansion slots

AGP - Video card

AMR - Modem, Sound card

CNR - Modem, Network card, Sound card

EISA - SCSI, Network card, Video card

ISA - Network card, Sound card, Video card

PCI - Network card, SCSI, Sound card, Video card

PCI Express - Video card

VESA - Video card

AGP

Short for Accelerated Graphics Port, AGP is an advanced port designed for Video cards and 3D accelerators. Designed by Intel and introduced in August of 1997, AGP introduces a dedicated point-to-point channel that allows the graphics controller direct access to the system memory. Below is an illustration of what the AGP slot may look like on your motherboard.

The AGP channel is 32-bits wide and runs at 66 MHz, which is a total bandwidth of 266 MBps and much greater than the PCI bandwidth of up to 133 MBps. AGP also supports two optional faster modes, with a throughput of 533 MBps and 1.07 GBps. It also allows 3-D textures to be stored in main memory rather than video memory.
AGP is available in three different versions, the original AGP version mentioned above, AGP 2.0 that was introduced in May of 1998, and AGP 3.0 (AGP 8x) that was introduced in November of 2000. AGP 2.0 added 4x signaling and was capable of operating at 1.5V and AGP 3.0 was capable of double the transfer speeds.

Where is AGP on the motherboard

Note: Today, AGP has been replaced by PCI Express.

A computer with AGP support has one AGP slot next to all other expansion slots or an on-board AGP video. If you needed more than one video card in the computer, you can have one AGP video card and one PCI video card or use a motherboard that supports SLI.

Tip: Not all operating systems support AGP because of limited or no driver support. For example, Windows 95 did not incorporate AGP support. If you are running an older version of Windows, see the Windows versions page for information about Windows versions that support AGP.

What is AGP Pro?

AGP Pro is an AGP interface extension specification for advanced workstations. This specification delivers additional power to video cards, includes an extended connector, thermal envelope, mechanical specifications, I/O bracket, and motherboard layout

AMR

Released September 8, 1998, AMR is short for Audio/Modem Riser and allows OEMs to make one card that has the functionality of either Modem or Audio or both Audio and Modem on one card. This specification allows for the motherboard to be manufactured at a lower cost and free up industry standard expansion slots in the system for other additional plug-in peripherals. The picture an example of what the AMR slot looks like on the Motherboard. This slot is often on the far edge of the motherboard

PCI

Short for Peripheral Component Interconnect, PCI was introduced by Intel in 1992. The PCI bus came in both 32-bit (133MBps) and 64-bit versions and was used to attach hardware to a computer. Although commonly used in computers from the late 1990s to the early 2000s, PCI has since been replaced with PCI Express.

Revisions came in 1993 to version 2.0, and in 1995 to PCI 2.1, as an expansion to the ISA bus. Unlike ISA and other earlier expansion cards, PCI follows the PnP specification and therefore did not require any jumpers or dip switches. The picture below shows an example of what PCI slots look like on a motherboard. As you can see, there are three PCI slots: PCI4, PCI5, and PCI6.

Examples of PCI devices

PCI device drivers

If you are looking for PCI drivers, you most likely need to download them for a specific PCI device. For example, if you need a PCI Ethernet adapter driver, you should install the drivers for the network card. See our drivers section for a listing of drivers for various devices.

CNR

Short for Communication and Network Riser, CNR is a specification that supports Audio, Modem, USB, and LAN interfaces of core logic chipsets. This technology and the CNR slot was first introduced by Intel February 7, 2000 and was mainly developed by leading hardware and software developers who helped release the AMR (Audio Modem Riser) slot. In the picture below is an example of a CNR slot, which is labeled as "CNR_SLOT" on this motherboard.

Today, this slot is no longer found on motherboards and has been replaced with PCI only motherboards and motherboards with PCIe.

EISA

Short for Extended Industry Standard Architecture, EISA or Extended ISA is a standard first announced in September of 1988 for IBM compatible computers that competed with the MCA bus. The EISA bus is found on Intel 80386, 80486 and early Pentium computers and was designed by nine competitors. These competitors were AST Research, Compaq, Epson, Hewlett Packard, NEC, Olivetti, Tandy, WYSE, and Zenith Data Systems.

The EISA bus provided 32-bit slots at an 8.33 MHz cycle rate for use with 386DX or higher processors. EISA can also accommodate a 16-bit ISA card in the first row.

Although the EISA bus is backwards compatible and not a proprietary bus, it never became widely used and is no longer found in computers today.

ISA

1. Short for Industry Standard Architecture, ISA was introduced by IBM and headed by Mark Dean. ISA was originally an 8-bit computer bus that was later expanded to a 16-bit bus in 1984. When this bus was originally released it was a proprietary bus, which allowed only IBM to create peripherals and the actual interface. However, in the early 1980's other manufacturers were creating the bus.

In 1993, Intel and Microsoft introduced a PnP ISA bus that allowed the computer to automatically detect and setup computer ISA peripherals, such as a modem or sound card. Using the PnP technology, an end-user would have the capability of connecting a device and not having to configure the device using jumpers or dip switches.

All recent computers today no longer included the ISA slots and instead are using more PCI, AGP, and other slots. Below is a graphic of what an ISA expansion card may look like as well as the slot it connects into on the motherboard.

PCI Express

Originally known as 3rd Generation I/O (3GIO), PCI Express, or PCIe, was approved as a standard on July 2002 and is a computer bus found in computers. PCI Express is a serial bus designed to replace PCI and AGP and is available in different formats: x1, x2, x4, x8, x12, x16, and x32. The data transmitted over PCI-Express is sent over wires called lanes in full duplex mode (both directions at the same time). Each lane is capable of around 250MBps and the specification can be scaled from 1 to 32 lanes. With 16 lanes PCI Express supports a bandwidth of up to 4,000MBps in both directions. Below are some graphic illustrations of what the PCI Express would look like on the motherboard.

VESA

Short for Video Electronics Standard Association, VESA is a group of monitor and video card manufacturers that set video display and bus standards. VESA was originally founded by NEC and is most well known for the VL Bus or VESA local Bus standard.

Many of the above expansion card slots are obsolete. You're most likely only going to encounter AGP, PCI, and PCI Express when working with computers today. In the picture below is an example of what expansion slots may look like on a motherboard. In this picture, there are three different types of expansion slots: PCI Express, PCI, and AGP.

Motherboard Port Guide: Solving Your Connector Mystery

12Comments

By Loyd Case, PCWorld

May 9, 2012 6:00 PM
Single
Page

Gigabyte 990FXA-UD7

Next we'll turn our attention to a motherboard that supports AMD CPUs. Note that AMD-chipset boards support many of the same features as Intel-based boards--that's the great thing about industry standards.

An AMD-compatible motherboard: the Gigabyte 990FXA-UD7.

24-pin ATX power: This connector exists on all current ATX-based motherboards, and is the standard means of connecting power from power supplies. This connector delivers power to all interfaces, including 3V, 5V, and 12V. The typical ATX12V version 2.3 PSU delivers up to 75W for PCI Express graphics cards; but numerous modern graphics cards need more than that, which is why you'll often find secondary six- or eight-pin power connectors on the graphics cards themselves.
ATX4P: This unusual item is actually a SATA power connector for delivering power to SSDs, hard drives, or optical drives from the motherboard itself.
TPM connector: Some off-the-shelf PCs and laptops use the Trusted Platform Module connector to link to a cryptographic processor module for storing encryption keys and handling dedicated encryption chores such as hard-drive encryption and certain types of digital rights management (DRM) decryption.
USB 3.0 front panel: This connector is used to drive front-panel USB 3.0 connectors. It requires more pins than USB 2.0 connectors do, but it drives two USB 3.0 ports instead of one. If your PC case lacks a USB 3.0 internal cable, you won't be able to use it. Like back-panel connectors, front-panel USB 3.0 ports are often color-coded blue.
AMD CPU socket: I'm calling out this component because its style differs from that of a modern Intel CPU socket. AMD CPUs still have pins, whereas Intel has moved the pins to the motherboard socket.

Intel DZ77GA-70K

I'm using a photo of just one section of this board, to call out some specific connectors and to get a little closer in. The Intel DZ77GA-70K motherboard is designed to accommodate the latest Intel Z77 chipset.

Part of the Intel DZ77GA-70K--a motherboard that hosts the latest Intel Z77 chipset.

Case fan header: As noted earlier, most higher-end motherboards have several of these fan headers scattered around the board. If enough of them are available, you should connect your fans to them, so that the BIOS can monitor and manage the fan speeds--unless you're a serious overclocker who uses separate fan-control modules.
PCI Express x4 slot: This relatively rare physical and electrical PCIe x4 slot is used for higher-performance networking cards and for some storage controller cards.
S/PDIF digital audio: This older type of connector was originally used to connect to CD-ROM drives. Today it's still used to connect to some optical drives and other audio devices that support S/PDIF (Sony/Philips Digital Interface) digital audio.
USB 3.0 front panel: The DZ77GA motherboard ships with two front-panel USB 3.0 connectors, driving up to four USB 3.0 ports on the front of the PC case.
High-current USB 2.0 front panel: This is a slightly different type of USB 2.0 connector. Though it acts as a normal USB 2.0 port when sending or receiving data, it can deliver extra current to permit fast charging of mobile devices, and it can even charge devices (like Apple's iPad) that requires more current than standard USB 2.0 normally delivers.
Consumer IR: This connector is used to attach front-panel infrared receivers, which enable users to control the PC via a standard programmable remote.
Diagnostic LEDs: Most motherboards have simple LEDs that light up or change color if the board experiences problems. A few higher-end boards, however, have these status LEDs, which flash an alphanumeric code that helps the user narrow down the source of a boot problem.
That wraps up our tour of various motherboard connectors, pins, and ports. Though I haven't covered all of the possibilities by any means, the ones listed here account for the vast majority of connectors you'll encounter on today's motherboards.
Rarely will you use every single connector on a board, but understanding these connectors should help you choose a PC case that suits your needs, or that accommodates new devices that you plan to add in an upgrade. Also, if you have a specific need, you'll be better able to shop for a motherboard capable of handling your application.

How to connect Panel LED and I/O Port to your motherboard

PANEL LED

Please follow MB manual to connect panel LED.

RESET SW　 (2-pin RESET) Connect RESET SW to MB , blue colors are “ + “
H.D.D LED　 (2-pin IDE_LED) Connect HDD.LED to MB , orange colors are “ + “
POWER SW　 (2-pin PWR SW) connect POWER SW , grey colors cables are “+”
POWER LED　 (3-pin PLED) connect POWER LED , green colors cables are “+”
SPEAKER　 (4-pin) connect SPEAKER , red colors cables are “+”

Jumper example: