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What is a Motherboard ?


Socket 939 ( K8)Socket 775 ( P4)


Socket 754 ( K8)Socket 478 ( P4)

Socket A/462 ( K7)Socket 423 ( P4)


Socket 7 ( K6)Socket 370 ( P3)



What is a Motherboard ?
It's the main circuit board of a computer. The motherboard contains the connectors for attaching additional boards. Typically, the motherboard contains the CPU (Main Processor Chip), BIOS, Memory (RAM), Storage interfaces (Hard Disk Drives), serial and parallel ports, expansion slots, and all the controllers required to control standard component devices, such as the monitor, keyboard, and drives. Collectively, all these chips that reside on the motherboard are known as the motherboard's chipsets.

What Form Factor Motherboard will fit my case?

Illustrations, pinouts, and specifications for standard pc ports

Parallel and Serial connectors

The parallel and serial ports are built onto the back of the motherboard. You would most likely connect a parallel printer to this port. Otherwise you may even connect a parallel or serial data cable.

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Power Connector (AT or ATX)

The industry standard ATX power-supply–to–motherboard main connector is the Molex 39-29-9202 (or equivalent) 20-pin ATX style connector.

As motherboards and processors evolved, the need for power became greater. In particular, chipsets and DIMMs were designed to run on 3.3v, increasing the current demand at that voltage. In addition, most boards included CPU voltage regulators designed to convert +5v power into the unique voltage levels required by the processors the board supported. Eventually, the high current demands on the +3.3v and +5v outputs were proving too much for the number and gauge of the wires used. Melted connectors were becoming more and more common as these wires overheated under these loads.
Finally, Intel modified the ATX specification to add a second power connector for ATX motherboards and supplies. The criteria was that if the motherboard needed more than 18A of +3.3v power, or more than 24A of +5v power, an auxiliary connector would be defined to carry the additional load. These higher levels of power are normally necessary in systems using 250-watt to 300-watt or greater supplies.

To augment the supply of +12v power to the motherboard, Intel created a new ATX12V power supply specification. This adds a third power connector, called the ATX12V connector, specifically to supply additional +12v power to the board.

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Connectors for (Floppy Disk Drive, Hard Disk or DVDRW Drive's)
Storage devices attach to these headers. The older style ribbon cables or new style round cables for the;



Floppy drive attach to (BLACK 34 pin connector)
Hard Disk drives or DVDRW attach to (BLUE [primary] AND WHITE [secondary] 40 pin connectors)
Raid type Hard Disk drives plug into (YELLOW 40 pin connectors)



Connectors for (Serial ATA Drive's)
Storage devices attach to these headers. The cables for the;

SATA Hard Disk drives attach to (ORANGE 7 pin connectors)

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Memory Sockets for (RAM)

240pin DDR2-533 DIMM attaches to (Green 240 pin connector)
240pin DDR2-400 DIMM attaches to (Orange 240 pin connector)
Supports Dual channel DDR2 memory architecture.

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USB Universal Serial Bus

USB version 2.0 is a "peripheral connection interface" for external devices. USB is supposed to be what you'll connect digital camera, joysticks, keyboards, modems, scanners, mice, and anything else that use USB ver. 2.0 interface. USB 2.0 is also backward compatible to USB version 1.1 type peripherals.


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PS2 Connectors (Mouse and Keyboard Connector)

PS/2 mouse plugs into the TEAL mini-din with 6 pin connector located at the back of the motherboard.

PS/2 keyboard plugs into the PURPLE mini-din with 6 pin connector located at the back of the motherboard.

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LAN - DSL/CABLE Connector (CAT5 cable or RJ45 Connector)

Your LAN CAT5 or RJ45 cable end

will plug into this port 8 pin connector located at the back of the motherboard.

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PC BACK side Connectors

(Firewire, 6pin, 4pin)
Your firewire cable cable end will plug into appropriate pin connector located at the back of the motherboard.
(Line Out, Line In, Microphone)
Your Speaker cable cable end will plug into GREEN HOLE connector located at the back of the motherboard.
Your Microphone cable cable end will plug into RED HOLE connector located at the back of the motherboard.
Your Audio Line Out cable end will plug into BLUE HOLE connector located at the back of the motherboard.
Your Rear Speaker cable cable end will plug into BLACK HOLE connector located at the back of the motherboard.
Your Center Sub Woofer Speaker cable cable end will plug into ORANGE HOLE connector located at the back of the motherboard.
Your *SPDIF cable cable end will plug into LIGHT GREEN SQUARE HOLE connector located at the back of the motherboard.
Your **SPDIF coaxial audio cable cable end will plug into SILVER ORANGE ROUND HOLE connector located at the back of the motherboard.

note: *SPDIF OUT1 (Optical) jack connects to SPDIF -supported devices such as MiniDisc (MD) recorder that have SPDIF optical connectors.
note: *SPDIF OUT1 (RCA/Optical) jack connects to SPDIF -supported devices such as DAT, MD recorder or speakers that have SPDIF connectors.

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CPU SOCKET (socket area where a or processer will be seated)

The CPU socket is the connector that interfaces between a computer's motherboard and the processor itself. Most CPU sockets and processors in use today are built around the pin grid array (PGA) architecture, in which the pins on the underside of the processor are inserted into the socket, usually with zero insertion force (ZIF) to aid installation.


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Pin Connectors for Case LED's (Flashing Lights) connections


These pins are found on the corner end of most motherboards and point straigt up. They are typically color coded so you can plug in the tiny wires from your PC case to get cordination of blinking lights from the LED's Light Emitting Diodes,  Once properly connected to these headers you will see Hard drive Activity and PowerOn indicator lights on the outside of the PC enclosure.

These pins connections are also used for functionality of having your PC turn on or off. Or even connecting a small internal PC speaker. You will also various 3 pin sets on the motherboard that will be labled for connection of main CPU fan or extra internal LED fans.

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CMOS battery
Complimentary Metal Oxide Semiconductor.  When the power of the mainboard is not present, this battery is low powered enough to help the silicon keep the required information as to the configuration of the PC.

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Basic Input Output System (BIOS) or Flash BIOS
This ROM chip controls the low level interactions between hardware and software. You now can download the latest flash bios instructions from most motheroboard manufactures websites.

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Expansion slots

These expansion slots follow the Peripheral Component Interconnect EXPRESS specifications as proposed by the PCI SIG (Special Interest Gup)

The PCI express subsystem consists of several PCI "lanes" 1 PCI lane was have a transfer rate of 250Mb/s in one direction and 500Mb/s in full duplex (both directions)

Instead of standard PCI slots you will now have x1PCI Express slots. Each of these slots will have access to an entire lane of the PCI express system. No longer will devices have to share the bandwidth available on the PCI bus. PCI devices on the original PCI bus shared the available bandwidth which was limited to 132MB/s. This shared by all the PCI devices in your system could but a strangle hold on your PCI bandwidth. This new system prevents this from ever being an issue.



Above is a picture of a x16 PCI Express slot (top) and a x1 PCI Express slot (bottom)

A x1 PCI Express slot can provide a maximum of 25W of power, you will find that this is more than enough for a single PCI device. A x16 PCI Express slot will have support for 75W of power (bear in mind that these days high powered graphics cards often draw extra power direct from the PSU)

Chart below is: PCI-X Vs. PCI Express




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Slots for Add on Cards using (Standard PCI)
These expansion slots follow the Peripheral Component Interconnect specifications as proposed by the PCI SIG (Special Interest Group).

ISA Slots
These expansion slots follow the Industry Standard Architecture as found on the early PCs introduced by the (Special Interest Group).

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Comparison of Form Factors (Motherboard Foot-Prints)

The most common motherboard form factor today is called ATX. Introduced by Intel Corp. in 1995 as an extension of the Baby AT form factor, ATX motherboards have a maximum size of 12 by 9.6 in. Smaller variants include the MiniATX, MicroATX and FlexATX. The less common EATX (Extended ATX) will likely be superseded by a new WTX form factor designed especially for workstations.

The newest motherboard form factor, Intel's BTX (Balanced Technology Extended), was announced last fall but isn't on the market yet; products should arrive later this year, however. BTX is mechanically similar to ATX but represents a technological update, allowing newer memory types, better thermal handling, faster storage (Serial ATA) and component (PCI-X) interfaces, two different heights (standard and low-profile) for components, and a greater range of board sizes.

 

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Video Chipset

The video chipset is the brains of the video card and determines what its capabilities are. Better chipsets are more efficient, include more acceleration features, and also include extended capabilities such as 3D acceleration or MPEG decoding. The chipset is one of the most important determining factors of overall video performance, if not the most important.

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What is a Chipset?

Every computer purchase, every motherboard upgrade, every CPU buying decisions comes back to the same thing: the system chipset. If the CPU is the brain of your PC, the chipset is its heart. It controls the flow of bits that travel between the CPU, system memory, and the motherboard bus. Efficient data transfers, fast expansion bus support, and advanced power management features are just a few of the things the system chipset is reponsible for.

Note that some of the above are not integrated with every chipset.

Every bit of information that is stored in memory or is sent to any I/O device has passed through the chipset on its way to the CPU.  You can think of the CPU as a terminus or node, while the chipset is the hub.  The chipset is all about Input/Output and multiplexing and data transfer.  Peripherals need the chipset to access other peripherals.

Have you ever heard of DMA?  Have you ever wondered how data bypasses the CPU on its way to the appropriate device?  The DMA controller inside the chipset does that.  What keeps data pouring in from the hard disk to the CPU from colliding with data from other devices?  The bus controllers (Memory, PCI) inside the chipset do that.

The chipset runs the show.  When new chipsets emerge, motherboard manufacturers redesign their boards to accommodate them.  Presently, more chipsets are having greater functionality, even as costs are staying relatively constant.

The CPU can be changed.  The memory can be upgraded.  The hard disk can be swapped.  But the motherboard has been designed around the capabilities of the chipset, and until you change the motherboard, your PC will function largely the same.

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Bracket Connectors (Case extensions for Sound, USB2 or Firewire ports)

These ports on the motherboard are the headers for connecting various industry standard extension brackets. Thus giving you more ease of use with pluging in and out devices to the front or back of the computer. Most motherboards ship one or two bracket connectors for added Sound, USB2 or Firewire IEEE1394 ports.


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Illustrations, pinouts, and specifications for standard pc ports

Illustrations, pinouts, and specifications are provided for the following ports:

Ethernet

Pin

Assignment

1

Transmit+

2

Transmit-

3

Receive+

4

(Reserved)

5

(Reserved)

6

Receive-

7

(Reserved)

8

(Reserved)

IEEE 1394

Pin Assignment
1 Power
2 Ground
3 B-
4 B+
5 A-
6 A+
 

USB

Pin Assignment
1 Power
2 - Data
3 + Data
4 Ground

Parallel Port

IEEE 1284-C for a Printer

 
Pin Assignment Pin Assignment
1 STROBE 14 AUTOFD
2 DATA[0] 15 FAULT
3 DATA[1] 16 INIT
4 DATA[2] 17 SELIN
5 DATA[3] 18 GND
6 DATA[4] 19 GND
7 DATA[5] 20 GND
8 DATA[6] 21 GND
9 DATA[7] 22 GND
10 ACK 23 GND
11 BUSY 24 GND
12 ERROR 25 GND
13 SELECT

 

Serial Port

Pin Assignment


1 DCD Data Carrier Detect
2 RD Receive Data
3 TD Transmit Data
4 DTR Data Terminal Ready
5 SG Signal Ground
6 DSR Data Set Ready
7 RTS Request to Send
8 CTS Clear to Send
9 RI Ring Indicator

Monitor

 
Pin Assignment
1 Red
2 Green
3 Blue
4 Ground
5 Ground
6 Red Return
7 Green Return
8 Blue Return
9 No Connect
10 Ground
11 Ground
12 IIC Data
13 Horizontal Sync
14 Vertical Sync
15 IIC Clock
 

Microphone and Speaker/Headphones

Microphone

Tip 

Ring

Sleeve

Silicon Graphics supplied electret mono microphone

Signal(+)

Signal(+)

Ground(-)

Line-level mono microphone

Ground (-)

Signal (+)

Ground (-)
 

Microphone Jack

Connector

3.5 mm stereo mini (mono signal on tip and ring)

Power

+5 phantom power on tip

Type

Unidirectional electret condenser

Speakers

Power

6 W (average) per channel

Frequency range

180 Hz - 15 KHz

Magnetic flux leakage

<50 mGauss @2 cm

Input impedance

150 ohms

Signal connector

3.5 mm stereo mini

Power connector

2.5 mm mono micro
 

Headphone

Recommended impedance

35 ohms

Connectors

3.5 mm stereo

Analog Line-Level Audio

 

Specifications

Line In

Line Out

Line level

-10 dBV

-10 dBV

OdBFS Maximum

+10 dBV to -22 dBV

6.5 dBV 0.5 dBV

Coaxial Digital Audio

Optical Digital Audio

Composite Video

Svideo

Silicon Graphics 1600SW Flat-Panel Monitor Port


36-Pin (F)



Pin Assignment Pin Assignment
1 ODDCH0_N 19 ODDCH3_N
2 ODDCH0_P 20 ODDCH3_P
3 ODDCH1_N 21 ODDCLK_N
4 ODDCH1_P 22 ODDCLK_P
5 ODDCH2_N 23 12C_SCL
6 ODDCH2_P 24 12C_SCL
7 1394_IN_N 25 12C_SDA
8 1394_IN_P 26 12C_DGND
9 LVDSGND 27 USB/12C_VCC
10 LVDSGND 28 USB/12C_GND
11 1394_OUT_N 29 USB_DATA
12 1394_OUT_P 30 USB_CLK
13 EVNCH0_N 31 TXR_ENABLE_NOT
14 EVNCH0_P 32 DGND
15 EVNCH1_N 33 EVNCLK_N
16 EVNCH1_P 34 EVNCLK_P
17 EVNCH2_N 35 EVNCH3_N
18 EVNCH2_P 36 EVNCH3_P


DVI Digital Visual Interface .. standard for high-speed, high-resolution digital displays. Developed by the Digital Display Working Group (DDWG).
READ THE DVI TUTORIAL

Digital Video Broadcasting/Digital Audio-Visual Council (DVB/DAVIC), developed by DAVIC and DVB and adopted by European Telecommunication Standards Institute (ETSI) and International Telecommunication Union (ITU)

DVI has a number of different types connectors:
DVI-D Digital only connector; 24 pins [modified D style]
DVI-I Digital and Analog [RGB]; 29 pins [modified D style]
DFP Digital only connector






DVI was developed by the Digital Display Working Group (DDWG). It carries the same type of signal as the DFP connector; however, the connector is not the same physically or in terms of pin out. The DVI connector comes in two forms, a 24-pin version and a 29-pin version. The 29-pin version allows an analog signal to also be carried. Signal type: analog and digital

pin 1 - TMDS Data 2-
pin 2 - TMDS Data 2+
pin 3 - TMDS Data 2/4 Shield
pin 4 - TMDS Data 4-
pin 5 - TMDS Data 4+
pin 6 - DDC Clock
pin 7 - DDC Data
pin 8 - Analog Vertical Sync
pin 9 - TMDS Data 1-
pin 10 - TMDS Data 1+
pin 11 - TMDS Data 1/3 Shield
pin 12 - TMDS Data 3-
pin 13 - TMDS Data 3+
pin 14 - +5 V Power
pin 15 - Ground
(+5 V, Analog H/V Sync)
pin 16 - Hot Plug Detect
pin 17 - TMDS Data 0-
pin 18 - TMDS Data 0+
pin 19 - TMDS Data 0+
pin 20 - TMDS Data 0/5
Shield
pin 21 - TMDS Data 5 -
pin 22 - TMDS Data 5+
pin 23 - TMDS Clock Shield
pin 24 - TMDS Clock+
pin C1 - TMDS Clock-
pin C2 - Analog Red Video Out
pin C3 - Analog Blue Video Out
pin C4 - Analog Horizontal Sync
pin C5 - Analog Common Ground
Return (R, G, B Video Out)

DVI Tutorial

1) What is the difference between Dual Link and Single Link? Which do I need?
Dual link enables a higher resolution (1920 X 1080) and more channels. You can view 2 displays simultaniously. If in doubt, order the Dual Link cable because it is backwards compatible with Single Link.

2) I need a DVI-I to DVI-D cable - What part number do I buy?
A DVI-I enables digital and analog signals. A DVI-D only allows digital signals. The part number to buy is DVIDL-length

3) Why are your DVI cables so much less?
You are coming right to the source. Our cables meet all wiring specifications. We don't know why everybody else is so expensive.

4) Is there a distance limitation?
Yes. For digital DVI cables there is a 5 Meter distance limitation. If you go longer the video results will be unpredictable and not guaranteed. The only way to safely and efficiently go longer distances is to use our OC and OLC series DVI fiber cables.

5) What is the TFT LCD?
TFT stands for "Thin Film Transistor" and describes the control elements that actively control the individual pixels. For this reason, one speaks of so-called "active matrix TFT's". LCD means "Liquid Crystal Display" and stands for monitors that are based on liquid crystals.

6) What's the difference between CRTs size and TFT size?
The visible diagonal size of a CRT tub monitor is always smaller than the tube's actual diagonal size. For example: a 17-inch CRT monitor has an edge area and it's visible diagonal is only 16-inches. But TFT LCD monitors do not have an edge area. This means that a 15-inch TFT LCD monitor is almost the same as the 17-inch CRT monitor.

7) What's the Contrast Ratio?
The Contrast Ratio is derived from the maximum and the minimum values for brightness.

8) What's the difference netween Digital and Analog Interface? Any advantages or disadvantages?
TFT LCD monitors with an analog VGA interface dominate the market. Because it is easy to install PC basis and not purchase a new graphics board. Although digital TFT LCD monitors don't need to adjust clock and phase and the no signal losses advantage. The Digital Interface standard has totally different connectors and it is not easy to buy a suitable graphic board. So the analog TFT LCD monitors still dominate the market. The following table gived you an overview of the most important points:
Digital Control Analog Control
Advantages
  • No signal losses due to DA and AD conversion
  • Geometry, clock and phase settings unnecessary - therefore simple to use
  • Lower costs as less electronic circuitry required
Disadvantages
  • Currently three standards (P & D (M1DA), DFP, and DVI)
  • Low availability of models with digital interfaces
  • Requires graphic board with digital output
 Advantages
  • Compatible with standard VGA boards on a broad installed PC basis
  • Not necessary to purchase seperate board
Disadvantages
  • Clock and phase of the TFTs must be synchronized with the analog signal to avoid pixel jitter, which is a relatively complex issue
  • Cables sensitive to external influences
  • High cost of signal conversion inside the display
  • Upgrade to digital interface not possible


9) How many Digital Interfaces are there now? Which one do I choose?
Currently there are three digital interface standards (P & D (M1DA), DFP, and DVI) in the market. The following table is the comparison and summary of the three interface standards. According to the table, DVI will be a standard in the future. DVI not only allows high resolutions, it also enables the connection of analog devices.
Standard P & D (M1DA) DFP DVI
Owner VESA (Video Electronics Standards Organization) DFP Group (Digital Flat Panel Group) and later VESA DDWG (Digital Display Working Group)
Revision / Date 1.0 / Jun 06, 1997 1.0 / Feb 14, 1999 1.0 / Apr 02, 1999
Web page www.vesa.org www.dfp-group.org www.ddwg.org
Workgroup leader VESA Compaq Intel
Compatibility Own standard P & D (M1DA) compatible (adapter possible) P & D (M1DA) and DFP compatible (adapter possible)
Transfer protocol TMDS - Transmission Minimizing Differential Signaling (PanelLink) TMDS (PanelLink) TMDS (PanelLink)
Max. Pixel rate (Dot Clock) 165 MHz x 1 165 MHz x 1 165 MHz x 1
Max. number of channels 3 channels (single link) 3 channels (single link) 6 channels (dual link)
Color depths 12 or 24 bit 12 or 24 bit 12 or 24 bit
Max. Resolution SXGA (1280 x 1024) SXGA (1280 x 1024) HDTV (1920 x 1080)
Optional transfer of other signals possible using the same connector Analog VESA video, USB, IEEE 1394-1995 No, only digital video Analog VESA video
Digital Connector P & D (M1DA)-D (30 pin) MDR20 (20 pin) DVI-V (24 pin)
Analog/Digital combination connector P & D (M1DA)-a/d (30+4 pin) No DVI-I (24 + 4 pin)
Connector width 40.6 mm 33.4 mm 37.0 mm


10) What do the connectors look like?
Below are images of the DVI connectors.



DVI-I Connector


DVI-D Connector


DFP Connector


ADC Connector
(Apple Proprietary Connector)
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