Understanding Your Motherboard - Internal

Understanding your motherboard is about pointing out what the bits of your motherboard actually do, if you are not used to building or upgrading your own machine you will want to know the ins and outs of the motherboard. The motherboard is a very important piece of equipment in your PC as it is connected to everything. Anything of major importance is plugged straight into the board. Some things on a motherboard are meant to be changed and altered to suit your own specifications, other things are strictly to be left alone unless fully qualified. We will try to give you a brief bit of history if there is any on each of these parts and some specifications. 

We will start with the internal connecters and ports and then move on to the External ones. You can use the numbers on the image to jump straight to that section.

  1. PCI Slot
  2. AGP slot
  3. North Bridge
  4. CPU Socket
  5. DIMM Slot
  6. Battery
  1. Molex Power connector
  2. IDE Ports
  3. S-ATA Ports
  4. South Bridge
  5. USB 2.0 Header
  6. Firewire Header

1 - PCI (Peripheral Component Interconnect) slot 

The PCI bus was developed by Intel, however This local bus is not only for Intel produced micro processors, you will find it very difficult to find a motherboard without a PCI slot on it. You will find that you will get a number of PCI slots from 1 up to about 6. The PCI bus runs at 33Mhz and normally 32bits. The PCI bus was the first one to fully support plug and play, where IRQ's and other resources are set up by the OS and there are no need to alter jumpers etc on the hardware. The PCI bus supports a wide range of peripherals from sound cards to DVD decoders and graphics accelerators. PCI is now the standard for internal peripherals except for graphics cards which have now moved over to the faster AGP port.

2 - AGP (Accelerated Graphics Port)

The AGP was designed specifically for video cards. AGP was really forced in to the computer world as graphics cards required more and more bandwidth. AGP provided not only a faster bus speed (66Mhz 1x  - 133Mhz 2x - 266Mhz 4x effectively) but allowed fast access to the main memory allowing for greater storage space in the memory for textures etc. Unlike the ISA and PCI local buses the AGP is a port and not a bus, this is because it is not expandable, it only involves the two devices the graphics card and the CPU. AGP still uses 32bits but is based on the PCI 2.1 standard which allowed 66Mhz transfer rate instead of 33Mhz.

Not on Picture - ISA (Industry Standard Architecture) slot 

The ISA slot is an old type of connector for internal peripherals such as modems and network cards. ISA is a system bus running a lot slower than the PCI and AGP bus speeds. ISA runs at only a 8Mhz maximum, although some systems do allow this to be overclocked to 12Mhz. Still very slow and as new motherboards are introduced the ISA slot is being left behind. It is hard to find components for the ISA bus now, if you are looking for ISA components then second hand stores are the best place to look, Network cards, sound cards and modems can still be found. ISA is a 16 bit bus, allowing for 16bits of data to be sent simultaneously.

3 - Chipset - North Bridge (with heatsink)

The Motherboards chipset can be described as what sets it apart from other boards in its category. Different chipsets contain different features and components. A chipset is a number of integrated circuits built onto the board to provide specific functions e.g. one part of the chipset may be an onboard component such as a modem or sound chip. Other parts may be used to control the CPU functions. Most chipsets are designed to work with only one "class" of CPU although now many older chipsets support more than one type of CPU such as socket 7 which supports the Pentium, Cyrix 686, Cyrix MII, AMD K6 and K6-2. There are certain restrictions though to what type of processor a chipset can handle because of the logic that the CPU uses to access the memory and its cache etc. Since these chips are working harder with each generation, motherboard manufacturers have started to put heatsinks on the main parts of the chipset to disperse some of the heat. For more information on chipsets see our What does a chipset do article.

4 - CPU (Central Processing Unit) socket

All the CPU "sockets look very similar, however they are different in the way they have different amount of pins and in different layouts. Because of this getting the right one is essential. A socket 7 CPU and a socket A CPU as well as a socket 370 CPU all look the same from above but will not fit in each others sockets. As well as sockets, Motherboards can also have CPU slots, slots look completely different to the image above of a CPU socket. If any of you own a N64 console or an older Sega Mega Drive you will no what a cartridge looks like. Slot CPU's are not much different to this.

5 - DIMM (Double Inline Memory Module) slots

These are by far the most common memory slots at the moment, the others are SIMMs (Single Inline Memory Module) and RIMM's (Rambus Inline Memory Module). DIMM's are used on virtually every board except for those on early P4 boards which predominantly use RIMM's. The standards for DIMM's are PC100 and PC133 and DDR266/33/400. PC100 is memory running at 100Mhz and PC100 at 133Mhz. DDR is Double Data Rate memory which effectively doubles the speed of the memory giving greater speeds i.e. 266/33/400 Mhz

6 - Motherboard Battery

The battery gives the board a small amount of power in order to store some vital data on your machine when the power is off. Data stored is that like the time and date so you don't have to reset them every time you boot the machine up. Motherboard batteries are usually long lasting Lithium batteries. Removing this can reset all the data on your machine including the BIOS settings, however not replacing this correctly can lead to irreparable damage to the motherboard. Only remove the battery if it is dead or if you can't have access any other way to resetting the data on your machine by use of the clear CMOS jumper or something similar.

7 - ATX Power connector

The standard ATX power connector, the cable for this will be coming from the PSU, a clip is normally provided to make sure you get them in the correct order. As a tip, don't try to push too hard if its stuck, check to see that it is in the correct way, I have seen plenty of power connectors where the pins have pushed out some of the connectors, these can be difficult to get back into place, so its best to be careful. 

8 - IDE connector 

The connector to which you will insert an IDE cable (supplied with motherboard) IDE cables connect devices such as hard disks, CD Drives and DVD Drives. The current 3 standards of IDE devices are ATA 33/66/100. the numbers specify the amount of data in Mb/s in a max burst situation. In reality there is not much chance of getting a sustain data rate of this magnitude. Both the connectors and devices are backwards compatible with each other, however they will only run at the slowest rated speed between them. All IDE cables will come with a red line down one side, this red line is to show which way it should be plugged in. The red line should always connect to pin one of the IDE port. Checking your motherboard documentation should show you which end is pin one. In some cases it will be written on the board itself.

In the case of ATA 66/100 there is a certain order that you plug devices in, the cable is colour coded to help you get them in the correct order.

9 - Serial ATA Connector

Serial ATA or more commonly seen as S-ATA is a new way of connecting your Hard Drives to your PC. S-ATA drives have the capability of being faster than the IDE counterparts and also have smaller thinner cables which help with the airflow of the system. S-ATA hard disks are fast becoming the norm for hard drive technology. Make sure your next motherboard has S-ATA connectors on-board.

Not in Picture - Floppy Drive Connector 

More simple than the IDE connector you only have to remember to get the red line to pin 1 of the connector and the red line to pin 1 on the floppy drive, This port is only to be used with floppy drives. 

10 - Chipset - South Bridge

When we talk about chipsets you mainly only ever hear about the North bridge. Even those into PC technology have a hard time naming the south bridges without looking them up. Names like Nforce 2 and KT600 are North bridges. The South Bridge does an important job as well. It handles things like the PCI bus, onboard Network and sound chips as well as the IDE and S-ATA buses. For more information on chipsets see our What does a chipset do article.

Not on Picture - BIOS (Basic Input Output System) Chip

The BIOS holds the most important data for your machine, if configured incorrectly it could cause your computer not to boot correctly or not at all. The BIOS also informs the PC what the motherboard supports in terms off CPU etc. This is why when a new CPU is introduced that physically fits into a slot or socket you may need a BIOS update to support it. The main reason for this is that different CPU's use different logics and methods and so the BIOS has to understand certain instructions from the CPU to recognise it.

11 - USB 2.0 header

As well as having USB ports on the rear of the motherboard, motherboard manufacturers often add a couple of USB headers so you can connect optional cables for extra USB ports. These cables are often supplied and you only need to add them on if you need the extra connectivity. USB 2.0 replaced USB 1.1 as a much faster solution. It is backwards compatible meaning all USB 1.1 devices will work in these new USB 2.0 ports.

12 - Firewire header

Firewire is also known as IEEE 1394. It is basically a high performance serial bus for digital and audio equipment to exchange data. The technology preceded USB but yet is faster than any current USB port. Often used for transferring digital video to the PC straight from a digital camera. The FireWire header onboard means you can install a FireWire port on your machine. Again these cables are often supplied as an optional extra which you will need to check with the retailer to see if they are supplied with your board.