OK, I'll start with one of the most common components we usually have users check, the CMOS Battery.
Complimentary Metal Oxide Semiconductor is a chip used to store information the motherboard needs to be able to boot. It is a form of volatile memory and is powered by a battery to hold its information when the computer is shut down.
This battery sits in a socket on the motherboard, and supplies power to the CMOS chip, which holds the Basic Input Output System information. That includes what hard drives are installed, memory settings, serial ports that are enabled and much more
Complimentary Metal Oxide Semiconductor is a chip used to store information the motherboard needs to be able to boot. It is a form of volatile memory and is powered by a battery to hold its information when the computer is shut down.
This battery sits in a socket on the motherboard, and supplies power to the CMOS chip, which holds the Basic Input Output System information. That includes what hard drives are installed, memory settings, serial ports that are enabled and much more
Jumpers...
Jumpers are a common subject around here, and they are used for a couple of different purposes. Hard drives have jumpers to determine whether a certain drive will be Master or Slave, same for CD ROM drives, and motherboards have jumpers to set bus speeds among other things.
Newer motherboards usually only have one bus speed jumper, it will set 100/133 MHz. Most of the AMD XP xxxx+ series boards use 133MHz. If your XP 1700+, for example, is detected as a 1100 mhz...change the jumper to 133 MHz.
Older boards had groups of jumpers to determine bus speed, multiplier and voltage. This picture came from a board of that type, it shows a single jumper in the background and a jumper block in the foreground. The jumpers are blue plastic, the fittings they match are called headers
Jumpers are a common subject around here, and they are used for a couple of different purposes. Hard drives have jumpers to determine whether a certain drive will be Master or Slave, same for CD ROM drives, and motherboards have jumpers to set bus speeds among other things.
Newer motherboards usually only have one bus speed jumper, it will set 100/133 MHz. Most of the AMD XP xxxx+ series boards use 133MHz. If your XP 1700+, for example, is detected as a 1100 mhz...change the jumper to 133 MHz.
Older boards had groups of jumpers to determine bus speed, multiplier and voltage. This picture came from a board of that type, it shows a single jumper in the background and a jumper block in the foreground. The jumpers are blue plastic, the fittings they match are called headers
CD ROM showing jumper positions
CPU
The metal case your computer is in IS
NOT the CPU...the CPU is an IC chip mounted in a socket on the
motherboard, containing millions of transistors.
CPU speed is measured in megahertz (MHz). One MHz means one million cycles per second. Gigahertz (GHz) means a thousand megahertz. That means the newer 1GHz plus processors cycle one billion times per second or more. Note the pins missing on two front corners for orientation, forming a diagonal on each corner. These must fit the socket in a specific position to function properly.
AGP/PCI slots
If you work on your own computer you need to know what slots you have, especially if you need to purchase parts -say a video card- and the salesman asks if you need an AGP or PCI card.
The Accelerated Graphics Port is a video specific slot, 2 7/8" long, usually brown in color and it sits almost 2 1/2" from the edge of the motherboard. Peripheral Component Interconnect is white, 3 3/8" long and 1 1/2" from the edge of the board.
If you work on your own computer you need to know what slots you have, especially if you need to purchase parts -say a video card- and the salesman asks if you need an AGP or PCI card.
The Accelerated Graphics Port is a video specific slot, 2 7/8" long, usually brown in color and it sits almost 2 1/2" from the edge of the motherboard. Peripheral Component Interconnect is white, 3 3/8" long and 1 1/2" from the edge of the board.
PS/2 is the interface used for mouse and keyboard, replacing the older
AT keyboard and serial mouse used on legacy systems. Both are the same
size, about 5/16" diameter, and are usually the first plugs on the left
as you face the edge of the motherboard that has all the plugs and ports
mounted on it.
Mouse is always on top and green, keyboard is on bottom and purple. They are denoted in this picture with the letters M and K scribbled in.
Mouse is always on top and green, keyboard is on bottom and purple. They are denoted in this picture with the letters M and K scribbled in.
USB
Universal Serial Bus is a fairly recently
implemented method of connecting peripherals to the computer. The USB
ports are fairly simple to recognize, as with most of the other ports
and plugs nothing else looks quite like them. You'll find USB used for
mice, keyboards, printers, web cams, digital cameras, and other items.
The USB ports are usually adjacent to the PS/2 mouse and keyboard plugs, immediately to the right of them.
The USB ports are usually adjacent to the PS/2 mouse and keyboard plugs, immediately to the right of them.
Serial/Paralell Ports
Serial and parallel ports have been around since the beginnings of
desktop computing. Serial ports have been used for mouse and external
modem connections, and parallel ports are used for older printers and
scanners. Newer ones use the USB interface. Often you will see the
parallel port listed as LPT, and serial ports called or printed as COM
ports.
The LPT port sits on top, and two serial ports (COM 1 and COM 2) below. On many newer motherboards you will see only one COM port, the other position taken by the output plug for the onboard video. these are located immediately to the right of the USB ports on most boards.
The LPT port sits on top, and two serial ports (COM 1 and COM 2) below. On many newer motherboards you will see only one COM port, the other position taken by the output plug for the onboard video. these are located immediately to the right of the USB ports on most boards.
When I listed the slots in an earlier post, I neglected to put the ISA slot...
The ISA bus is an older and now almost completely phased out slot on the motherboard. PCI and AGP are both much faster, but I still like to have a couple of ISA slots around for hardware modems and even my trusty old Sound Blaster 16.
ISA is a black slot made in two sections that total 5 3/8" long, 7/8" from the edge of the motherboard, and if you have any at all nowadays it's only one. PCI has taken over the rest of the board.
The ISA bus is an older and now almost completely phased out slot on the motherboard. PCI and AGP are both much faster, but I still like to have a couple of ISA slots around for hardware modems and even my trusty old Sound Blaster 16.
ISA is a black slot made in two sections that total 5 3/8" long, 7/8" from the edge of the motherboard, and if you have any at all nowadays it's only one. PCI has taken over the rest of the board.
Standoffs
Standoffs are used to hold the motherboard onto the chassis of the case, and to isolate it against electrical ground. Standoffs are made of metal and plastic, which type is used depends on the mounting options provided in the case. Occasionally cardboard washers must be used with the brass hexagonal type or the silver rectangular clips to stop a ground problem.
Note the ever-present coffee stains on the sticky pad..
Standoffs are used to hold the motherboard onto the chassis of the case, and to isolate it against electrical ground. Standoffs are made of metal and plastic, which type is used depends on the mounting options provided in the case. Occasionally cardboard washers must be used with the brass hexagonal type or the silver rectangular clips to stop a ground problem.
Note the ever-present coffee stains on the sticky pad..
Audio Panel
This should have been posted above, along with the other back panel connectors, and was overlooked.
The audio input/output jacks are sometimes located to the right of the serial and parallel ports, and sometimes are located on a sound card, and will be visible in one of the slots.
Older sound cards had three black 1/8" jacks, (Sometimes 4), and were stamped in the backplate cover with either the name of the jack or a small picture, while newer ones and onboard sound usually have color coded jacks. The yellow jack above is the game port, the audio jacks below are:
Green: Speaker Out (LEFT)
Blue: Line In (Middle)
Red: Microphone in (Right, red or pink)
The audio input/output jacks are sometimes located to the right of the serial and parallel ports, and sometimes are located on a sound card, and will be visible in one of the slots.
Older sound cards had three black 1/8" jacks, (Sometimes 4), and were stamped in the backplate cover with either the name of the jack or a small picture, while newer ones and onboard sound usually have color coded jacks. The yellow jack above is the game port, the audio jacks below are:
Green: Speaker Out (LEFT)
Blue: Line In (Middle)
Red: Microphone in (Right, red or pink)
ATX Power Connector
Earlier computers such as the IBM XT and 286 used AT motherboards, the
ATX was designed while the 286 was still around and later became the
industry standard form factor.
ATX uses a different power connector, different power switch and usually the mouse, keyboard, LPT and Serial plugs are mounted on the edge of the motherboard which eliminates 3 or 4 short cables used with AT form factor boards.
NOTE: ATX uses a momentary contact switch rather than a standard on/off switch. Hold the power switch down for 4-5 seconds and the computer should shut down. The switch is connected to the motherboard by means of a small pair of wires, usually to a header block on the board which will also have pins to connect IDE LED, Reset switch, Power LED and Internal Speaker.
ATX uses a different power connector, different power switch and usually the mouse, keyboard, LPT and Serial plugs are mounted on the edge of the motherboard which eliminates 3 or 4 short cables used with AT form factor boards.
NOTE: ATX uses a momentary contact switch rather than a standard on/off switch. Hold the power switch down for 4-5 seconds and the computer should shut down. The switch is connected to the motherboard by means of a small pair of wires, usually to a header block on the board which will also have pins to connect IDE LED, Reset switch, Power LED and Internal Speaker.
AT Power Connector
AT was the earlier form factor, used up until the Pentium II series CPU
was released. The motherboards wer the same physical sizes, sometimes
would even fit in the same case, but had different power connectors.
The AT form factor used two power plugs from the power supply, labeled P8 and P9, and this power connector on the motherboard. The black wire of each connector MUST be placed in the MIDDLE of the motherboard connector when setting up an AT system.
In this picture the AT keyboard connector is visible in front and to the left of the power connector.
The AT form factor used two power plugs from the power supply, labeled P8 and P9, and this power connector on the motherboard. The black wire of each connector MUST be placed in the MIDDLE of the motherboard connector when setting up an AT system.
In this picture the AT keyboard connector is visible in front and to the left of the power connector.
Memory Slots
Motherboards use several types of memory, or RAM. Random Access Memory
is used a sa sort of scratch pad for the computer to store recently
used data and instructions, so they can be accessed later from temporary
memory, instead of the much slower hard drive.
RAM is volatile memory, which means it loses any stored information when the computer is powered down. Earlier boards used 30 pin or 72 pin SIMM memory, newer ones use 168 pin DIMM. Single Inline Memory Module and Dual Inline Memory Module were both used on some motherboards, such as the one pictured here, 168 pin DIMM and DDR memory can be found on some modern motherboards. (Double Data Rate).
In this picture the board is fitted with a pair of 72 pin SIMM memory modules, the 168 pin DIMM slots in front are empty. 72 pin SIMM, if you have the opportunity to use it, MUST be used in matching pairs. DIMM modules can be used singly or in pairs. 30 pin SIMM is similar to 72 pin, but smaller. None will interchange
RAM is volatile memory, which means it loses any stored information when the computer is powered down. Earlier boards used 30 pin or 72 pin SIMM memory, newer ones use 168 pin DIMM. Single Inline Memory Module and Dual Inline Memory Module were both used on some motherboards, such as the one pictured here, 168 pin DIMM and DDR memory can be found on some modern motherboards. (Double Data Rate).
In this picture the board is fitted with a pair of 72 pin SIMM memory modules, the 168 pin DIMM slots in front are empty. 72 pin SIMM, if you have the opportunity to use it, MUST be used in matching pairs. DIMM modules can be used singly or in pairs. 30 pin SIMM is similar to 72 pin, but smaller. None will interchange
Manual CD Eject
AGP Retainer Clip
Newer AGP video cards usually have a slot at the end of the card that
fits the clip pictured here. This clip fits in a notch on the end of the
lower section of the card, and MUST be pushed aside to remove the card.
This clip is a simple black plastic tab, others use a white bell shaped
button that must be pulled aside to remove the card.
Fan Connector
Onboard CPU/Case fan power connector:
Most contemporary motherboards have one or more commonly two power connectors for auxiliary fans. Most are identified by silk screened markings on the motherboard, different manufacturers use different markings. Some will be clearly marked CPU Fan and Aux fan, others FAN 1 and FAN 2.
These are 3 connector plugs and supply 12V DC to the fans needed to cool the CPU and to move air through the case for general cooling. As a general rule the CPU Fan header will be closer to the CPU, although a small few are far enough away I have had to solder on extra wire to make them reach.
Most contemporary motherboards have one or more commonly two power connectors for auxiliary fans. Most are identified by silk screened markings on the motherboard, different manufacturers use different markings. Some will be clearly marked CPU Fan and Aux fan, others FAN 1 and FAN 2.
These are 3 connector plugs and supply 12V DC to the fans needed to cool the CPU and to move air through the case for general cooling. As a general rule the CPU Fan header will be closer to the CPU, although a small few are far enough away I have had to solder on extra wire to make them reach.
RAM Clips
When RAM is installed it must be seated correctly or the computer will
not boot at all. to keep it in place, plastic clips are used which must
snap into place when installing new or replacement memory.
This is one of the easiest installations of any of the components, but sometimes can be difficult to reach due to the placement of drive bays inside the case.
To install RAM simply line up the notches in the RAM chip, ensure that it is aligned with the slot ends and push it straight down into the slot until the white end clips snap shut. I prefer to install RAM with the motherboard lying flat on the workbench, but it can be installed after the motherboard is mounted in the case if done with care.
This is one of the easiest installations of any of the components, but sometimes can be difficult to reach due to the placement of drive bays inside the case.
To install RAM simply line up the notches in the RAM chip, ensure that it is aligned with the slot ends and push it straight down into the slot until the white end clips snap shut. I prefer to install RAM with the motherboard lying flat on the workbench, but it can be installed after the motherboard is mounted in the case if done with care.
USB Headers
Onboard USB Headers
Most newer motherboards include extra onboard USB headers, to enable the use of USB outlets on the front of newer cases. These headers are usually not in a standard location, trying to illustrate the various locations is beyond the scope of this thread. Usually the manual will include diagrams pointing out the locations of most headers, jumpers and switches, so check your manual.
The USB headers are either 8 or 10 pin, (usually 8) and have pinouts for two USB outlets. The pinouts for these are also non-standard, again consult your manual for the proper wiring. The red arrows point to the USB 1 and USB 2 designations silk screened onto this motherboard.
The USB cable should be one of two types. Generic cases usually have separate connectors on each of 8 wires, each marked to designate where it goes on the header. The commercial manufacturers such as Dell, Gateway and HP usually use a single plug that conforms to their own wiring diagram, and often will not match the pinouts of a retail motherboard available to consumers.
Most newer motherboards include extra onboard USB headers, to enable the use of USB outlets on the front of newer cases. These headers are usually not in a standard location, trying to illustrate the various locations is beyond the scope of this thread. Usually the manual will include diagrams pointing out the locations of most headers, jumpers and switches, so check your manual.
The USB headers are either 8 or 10 pin, (usually 8) and have pinouts for two USB outlets. The pinouts for these are also non-standard, again consult your manual for the proper wiring. The red arrows point to the USB 1 and USB 2 designations silk screened onto this motherboard.
The USB cable should be one of two types. Generic cases usually have separate connectors on each of 8 wires, each marked to designate where it goes on the header. The commercial manufacturers such as Dell, Gateway and HP usually use a single plug that conforms to their own wiring diagram, and often will not match the pinouts of a retail motherboard available to consumers.
Audio Cable:
CD/DVD ROM drives are designed to allow playback of audio CD's. That means the audio signal must be sent to the sound card, so the systenm can amplify it and send it to the speakers.
An Audio cable is used for that purpose. This picture shows the two types of plugs used both at the CD/DVD ROM end and the sound card end. The black plug is the more common one, and is a standard analog audio plug, the white one is a digital audio plug. Which one is used depends on your sound card.
When connecting these to the sound card or motherboard be sure and check the manual or silk screened designations on the card or board, most have a main audio input and an auxiliary. The main is the one normally used, auxiliary is only used when connecting two CD/DVD ROM drives to allow sound capability with both.
CD/DVD ROM drives are designed to allow playback of audio CD's. That means the audio signal must be sent to the sound card, so the systenm can amplify it and send it to the speakers.
An Audio cable is used for that purpose. This picture shows the two types of plugs used both at the CD/DVD ROM end and the sound card end. The black plug is the more common one, and is a standard analog audio plug, the white one is a digital audio plug. Which one is used depends on your sound card.
When connecting these to the sound card or motherboard be sure and check the manual or silk screened designations on the card or board, most have a main audio input and an auxiliary. The main is the one normally used, auxiliary is only used when connecting two CD/DVD ROM drives to allow sound capability with both.
Power Connectors:
These are the power connectors used to supply electrical power to the drives and fans inside the case. The larger one fits a plug on hard drives and CD ROM drives, the smaller one fits floppy drives.
In some cases extra power plugs will be needed, in that case splitters and adapters are available to provide an extra plug, more length or a power plug to fit and reach a case fan.
These power plugs are attached to the ends of wires coming from the power supply, and are keyed so they can only be attached one way, eliminating the possibility of reversing polarity and damaging components. They carry 5 and 12V DC. Check your motherboard manual for specific voltages.
These are the power connectors used to supply electrical power to the drives and fans inside the case. The larger one fits a plug on hard drives and CD ROM drives, the smaller one fits floppy drives.
In some cases extra power plugs will be needed, in that case splitters and adapters are available to provide an extra plug, more length or a power plug to fit and reach a case fan.
These power plugs are attached to the ends of wires coming from the power supply, and are keyed so they can only be attached one way, eliminating the possibility of reversing polarity and damaging components. They carry 5 and 12V DC. Check your motherboard manual for specific voltages.
DIP Switch:
This is a Dual Inline Pin switch used on some
motherboards for various settings, usually related to CPU speed, voltage
and multiplier. Some boards will have one and some two, each with a
specific purpose.
CPU Socket
This is the CPU Socket, where the CPU is mounted for use by the
motherboard. This one is a Socket 370, for Intel Pentium III and Celeron
processors, the Socket 462 (or Socket A) is for the newer AMD chips.
This socket is called a ZIF or Zero Insertion Force socket.
The red arrow points to a corner with the pins laid out diagonally for orientation of the CPU, the other corner (top left) is diagonal too, but not easily visible in the picture. This is to make sure the CPU can only be installed in one direction, so the numerous pins are all in the right places. The pins on the underside of the CPU fit the holes in the socket, which are connected underneath to the circuitry of the motherboard, to carry signals to and from the CPU, RAM and other components.
The lever at left is the lock down. When raised the CPU can be installed or removed, once installed it is lowered to the locked position which slides the lower section and holds the pins tight so the CPU cannot be removed.
The Pentium 4 CPU has a very similar socket, but smaller and with a different orientation method, while the slot style processors mount vertically in a long socket completely different from this one.
The heatsink mounts on top of the CPU and clips onto the tab sticking out on the front edge of this picture, and has another identical tab on the other side. A small metal clip holds the heatsink down.
The red arrow points to a corner with the pins laid out diagonally for orientation of the CPU, the other corner (top left) is diagonal too, but not easily visible in the picture. This is to make sure the CPU can only be installed in one direction, so the numerous pins are all in the right places. The pins on the underside of the CPU fit the holes in the socket, which are connected underneath to the circuitry of the motherboard, to carry signals to and from the CPU, RAM and other components.
The lever at left is the lock down. When raised the CPU can be installed or removed, once installed it is lowered to the locked position which slides the lower section and holds the pins tight so the CPU cannot be removed.
The Pentium 4 CPU has a very similar socket, but smaller and with a different orientation method, while the slot style processors mount vertically in a long socket completely different from this one.
The heatsink mounts on top of the CPU and clips onto the tab sticking out on the front edge of this picture, and has another identical tab on the other side. A small metal clip holds the heatsink down.
Heatsink/Fan
A mandatory compoent for all newer computers faster than about 200MHz or
so. The heatsink is usually made of aluminum and the fan mounted on top
of it to force air through the fins and help keep the CPU cooler.
Thermal compound should be applied betweeen heatsink and CPU, a very thin layer is usually best. The fan has a set of wires and a connector that plug into the motherboard to give it power. Most of the time your BIOS should have a section with temperature monitors, watch those for a couple of minutes and you can get an idea how hot or cool your CPU runs, at least at an idle. 115-125° F is about average for an idling computer.
The heatsink mounts by different methods, Pentium III and newer AMD chips use a heatsink design like the one shown here, P-4 chips have a larger heatsink that clips onto a plastic retainer mounted on the motherboard.
WARNING: DO NOT turn on your computer without the heatsink and fan mounted and securely fastened to the motherboard. Your CPU can and will get hot enough to destroy it in LESS THAN 15 seconds.
Thermal compound should be applied betweeen heatsink and CPU, a very thin layer is usually best. The fan has a set of wires and a connector that plug into the motherboard to give it power. Most of the time your BIOS should have a section with temperature monitors, watch those for a couple of minutes and you can get an idea how hot or cool your CPU runs, at least at an idle. 115-125° F is about average for an idling computer.
The heatsink mounts by different methods, Pentium III and newer AMD chips use a heatsink design like the one shown here, P-4 chips have a larger heatsink that clips onto a plastic retainer mounted on the motherboard.
WARNING: DO NOT turn on your computer without the heatsink and fan mounted and securely fastened to the motherboard. Your CPU can and will get hot enough to destroy it in LESS THAN 15 seconds.
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