This document includes basic introduction about motherboard, ill explain the basic contact very briefly and easy to understand there are very useful for hardware engineering.

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AIM:-TO STUDY CONNECTORS ON MOTHERBOARD.
Since no single motherboard contains every type of connectors, I've used
photos of four different boards to illustrate key examples. In one or two instances,
there is some overlap; but for the most part, connectors are mentioned only once.
Many of them may exist across different motherboard designs, however.
Asus P5WDH Deluxe
Let's start with an older motherboard, an Asus P5WDH Deluxe. This
motherboard has a few connectors that aren't included on current-generation boards,
as wll as some that do are still included, but are more readily visible here.
Connections on an older Asus P5WDH Deluxe motherboard.
Audio front panel:
This ten-pin connector links to the front-panel headphone and microphone
inputs. The particular connector shown is an AC97 connector, which existed prior to
multichannel HD audio. It's still in common use today.
Azalia digital audio header:

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You rarely find this connector, used to tie the motherboard to multichannel
digital outputs on the case, on current motherboards.
Serial-port header:
This connector isn't physically present on the board shown--you can just see the
solder points for it. But this header does appear on a few modern boards. It supports
a nine-pin, RS-232 serial port, usually as a bracket that occupies a slot space on the
back of the case. A number of RS-232 connections remain in use today, mostly in
point-of-sale devices or specialized test instruments. Consumer boards typically
don't have them.
FireWire (IEEE 1994a):
Once common as a digital camcorder interface, FireWire has largely been
supplanted by USB, and the motherboard makers are gradually phasing it out. Some
professional audio hardware still uses FireWire, though; you may also occasionally
find higher-speed IEEE 1394b headers, but they are even rarer.
USB 2.0 front panel:
These connectors are used to link to the front-panel USB ports on PC cases.
SATA connectors:
These components connect via cables to various storage devices, including hard-
disk drives, solid-state drives, and optical drives.
IDE connector:
Rarely found today, IDE connectors were used to link to older hard drives. In
addition, until a couple of years ago, many optical drives supported IDE. Today, all
new storage devices ship with SATA.
Floppy disk connector:
The venerable 3.5-inch floppy disk drive survived for nearly two decades--an
eternity in the tech universe. But unless you have a pile of old floppies, you won't
need a floppy drive. And if you do find yourself needing a floppy drive, you can
always pick up an external, USB-connected drive.

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Intel DP67BG
Now let's examine a more recent motherboard: an Intel D67BG, based on
Intel's P67 chipset and supporting LGA 1155 CPUs (like the Sandy Bridge-based
Core i7-2600K).
Intel D67BG motherboard: a modern Intel design.
DDR3 memory sockets:
Current-generation PC systems use DDR3 memory, but in many instances
they support different operating speeds. The P67 chipset used in this board maxes
out at DDR3-1600, but to achieve that level of speed you'd have to overclock the
chipset--officially the P67 supports only DDR3-1333. Here, we see four memory
sockets. The system supports dual-channel memory, meaning that the system is
populated with paired memory modules, which are mounted in sockets of the same
color.
CPU fan header:
This connector is specifically designed to link to the CPU cooling fan. The
system BIOS monitors CPU cooling fan speeds; and if the fan isn't connected to this
header, you may get an error at bootup.
Eight-pin ATX12V (CPU power) connector:

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Back when the Pentium 4 processor first shipped, Intel realized that high-
performance CPUs needed their own source of clean, dedicated power beyond what
the standard 24-pin power connector could deliver. Thus was born ATX12V. You'll
see four-pin connectors on lower-end boards supporting CPUs with lower thermal
design power (TDP), but the eight-pin version of the connector is used with higher-
end processors and on boards that users may overclock.
Power for secondary fans:
Many motherboards with secondary-fan power headers; these connectors are
mainly used to power and monitor various case fans.
PCI Express x1 connector:
PCI Express is a serial interface, though multiple lanes may be ganged
together. The "x1" refers to a slot supporting a single PCI Express lane; it is used for
I/O devices that don't require bidirectional bandwidth greater than 500 megabytes
per second (gen 1 PCIe). Sound cards, for example, are typically PCIe x1 devices.
PCI Express x16 (graphics):
PCI Express x16 slots are used mostly for graphics cards, though they can
be used with any PCI Express card. Confusion may arise, however, because not all
PCIe x16 slots are true PCIe x16. Occasionaly, you'll see PCIe x16 connectors that
are physical slots for accommodating graphics cards, but are actually eight-lane (x8)
or even four-lane (x4) electrically.
On some boards, even slots that support true 16-lane PCI Express for
graphics may revert to eight lanes if you install a second graphics card into a second
PCIe x16 slot on the motherboard. The P67 chipset, for instance, has only 16 total
PCIe lanes for graphics. So if you drop in two graphics cards to run in dual GPU
mode, each card will have just eight lanes available to it. This situation isn't as bad
as it sounds, though, since even eight lanes in a PCIe 2.0- or 3.0-based system
delivers plenty of bandwidth for most games.
32-bit legacy PCI slot:
The now-classic 32-bit PCI slot has been around since 1993. A host of
expansion cards support 32-bit PCI; and to accommodate them, most motherboards

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are likely to have at least one 32-bit PCI slot going forward. You may see some
system boards configured so that a particular back-panel case bracket can support
either a PCI slot or a PCIe slot, with some overlap between the two because they're
very close together.
Front-panel switch header:
This header connects various wires to the front panel of the case, where they
link to power and reset buttons, and status LEDs for power and storage-drive
activity.
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

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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.

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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.

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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.