What Does a Motherboard Do All Day?

All the other devices in your PC such as the microprocessor, memory, drives, multimedia cards, printer, and monitor all "plug" into the motherboard in one way or another. Once connected to the motherboard, each device is able to send data to the main memory. Main memory is a holding ground for the data and instructions the CPU needs in order to complete tasks. When the CPU requests data, the memory locates it, then sends it over to the CPU via a pathway on the motherboard called the system bus. When the processor finishes processing the data, it sends the result back to the memory, which in turn sends it back to the device that needs it. The motherboard's chipset coordinates and controls the speed and timing of those interactions.

 On the right is a diagram of a motherboard. Notice it is made up mostly of sockets, slots, connectors, and ports. The two primary exceptions are the chipset and the BIOS chip, which are built into the board.

The chipset is the most important part of a motherboard; it is largely responsible for the stability and performance of the board, and it determines which features are supported and which are not. Some well known motherboard chipset manufacturers include Intel, Via, SiS (Silicon Integrated Systems Corp.), AMD, and Nvidia. ATI has recently entered the core logic market as well.

The BIOS (basic input/output system) is responsible for booting up the computer when you first turn it on. It also helps control the flow of data between the operating system and hardware devices. Traditionally, the BIOS was on a ROM (read only memory) chip to ensure that its instructions would never be erased. However, all modern motherboards now have the BIOS on flash memory, which enables the BIOS to be "flashed" (updated) if desired. Further, most modern motherboards even have dual BIOS, which is described in more detail in "Special Features" below.

If you already know what CPU you'll be using, great. If not, start there. Think about what type of computer you want. Are you a gamer or someone who does a lot of image editing? If so, you may want a higher-end CPU such as an Intel P4, or an AMD AthlonXP. If you primarily use your PC for Microsoft Office and surfing the Internet, you may want an Intel Celeron or an AMD Duron. If you're not sure what you need, take a look at the Buyer's Guide chapter on CPUs.

Deciding on a CPU will help you narrow down your motherboard choices quite a bit. A motherboard will only support specific types and speeds of processors. For instance, a motherboard designed for an Intel P4 will not support an Intel PIII, and a motherboard designed for an Athlon processor up to 900MHz, will not support a 1400MHz Athlon. Also, it's important to understand that a motherboard will support either an Intel processor or an AMD processor, but not both. Intel and AMD (Advanced Micro Devices) are the two major manufacturers of processors.

In addition, you must purchase a motherboard that your CPU can physically connect to. The motherboard's slot or socket is where you will "plug in" your CPU. (See the CPU socket on the diagram.) Different CPUs come in different types of packaging, which only fit into certain slots or sockets. Therefore, if you know what type of slot or socket you need, you can eliminate all the boards that don't have it.

Before you purchase a motherboard, we urge you to contact the board's manufacturer and double check that it is definitely compatible with your CPU. Accidentally purchasing a board that doesn't support your CPU will put a major damper on your project.

The following are some of the latest CPUs and the socket types they require. Note that the latest processors use sockets rather than slots.

Everyone has different motherboard requirements depending on the type of system they want. However, the following is a list of basics we believe most people will benefit from having. Refer to the motherboard diagram above for a visual representation of the following features.

• ATX or MicroATX Form Factor: Form factor refers to the size and layout of your motherboard, as well as the type of case and power supply you need. Currently, most motherboards are ATX. Therefore, if you go with ATX you'll have a lot more options. (The motherboard in the diagram above is an example of an ATX board.)
  
  

  The second most popular form factor is MicroATX. MicroATX boards are smaller, which makes them more difficult to tweak or plug things into. In addition, there aren't as many sockets for memory, or expansion slots. On the other hand, they are usually less expensive, and a MicroATX case will save you space. A MicroATX board can also be used in an ATX case if needed.
  

• ATA/66, ATA/100, ATA/133 (EIDE): As mentioned in the SCSI section, SCSI and EIDE are your two drive interface options. EIDE (enhanced IDE) comes standard on most motherboards. However, different motherboards have different grades of EIDE. These days EIDE comes in four different bandwidths: 33MB/sec (ATA/33), 66MB/sec (ATA/66), 100MB/sec (ATA/100) and 133MB/sec (ATA/133). Getting a motherboard with ATA/133 will allow you to use ATA/133, ATA/100, ATA/66, or ATA/33 drives, because it is backward compatible. Unless you have an ATA/33 hard drive that you never plan to upgrade, don't opt for ATA/33. You can read more about EIDE in the Hard Drive Buyers' Guide.
• An AGP Slot: Most new graphics cards are designed to use AGP (accelerated graphics port) technology. AGP provides a fast data pathway between the video card and the computer's main memory. Formerly, most video cards were made for the PCI bus, which the AGP has surpassed in terms of speed and performance. PCI video cards are still available, but an AGP card is preferable. Choose either AGP4x, AGP8x or AGP Pro. The faster the slot is, the more bandwidth you have for transfering data from the rest of the system to your graphics card. Note that sometimes AGP slots require video cards of a certain voltage. For instance, many Intel boards have an AGP 4X slot that only supports video cards that are 1.5V. This means an older 3.3V video card would not be supported. You can read more about AGP in the Video Card Buyers' Guide.
• PS/2: This is the most common type of connector for a keyboard and mouse.
• Parallel Port: This is the most common type of port for your printer. Some scanners also use a parallel port connection.
• USB Ports ( 2 minimum ): USB 1.1 (universal serial bus) is a data pathway between main memory and peripherals that require a slow to medium data transfer rate such as joysticks, keyboards, and scanners. USB supports plug-and-play, which makes connecting plug-and-play equipped devices very easy. With plug-and-play a computer is supposed to be able to immediately recognize a newly connected device without the user having to configure anything.

  In addition, recently USB 2.0 has come to market. USB 2.0 offers up to 40% more bandwidth than USB 1.1, and is even slightly faster than FireWire (IEEE1394). This makes it more viable for devices such as external hard drives and CD-RW drives. In order to take advantage of a USB 2.0 port, however the device you wish to connect must also support the 2.0 specification.

• PCI Slots (4 minimum): Even if the PCI bus is no longer ideal for video cards, it is still used for other types of expansion cards such as sound cards, SCSI host adapter cards, IEEE 1394 (FireWire) cards, and network interface cards.

   

• DIMM, DDR DIMM, or RIMM Sockets: Make sure the motherboard can support the amount and type of memory your system needs. Motherboards that support DDR memory are currently very popular because DDR memory offers twice the bandwidth of standard SDRAM.

  As far as amount of memory, most systems require at least 64MB, and 128 is becoming pretty standard. If you want to use your system for graphic arts, publishing, and multimedia you'll probably want 256MB of memory or more for optimum performace. It's a good idea to leave yourself room for more memory should you need it.

Dual CPUs: Some motherboards support two CPUs. Dual CPU systems are well suited for small graphics workstations or servers.

• Dual Channel Memory: A Dual Channel motherboard uses Twin Bank mode and requires two memory modules plugged into the appointed DIMM slots. Each module is then controlled by a separate channel of the memory controller, which leads to greater efficiency: two sticks of 256MB RAM will perform better than one stick of 512MB RAM given that the two memory modules were designed for such operation and have identical chips and identical layouts.
• Dual BIOS: Dual BIOS technology is nice because if your primary BIOS fails for any reason the second BIOS will enable you to get your system back to an operating state so you can fix the problem. Most motherboards now have this feature.
• IEEE 1394 (FireWire) Port: IEEE (Institute of Electrical and Electronics Engineers) 1394 is a high performance serial bus. Currently, it is primarily used with peripherals requiring high, real time data transfer rates, such as video devices. Only one port is needed because up to 65 IEEE 1394 compatible devices can be daisy-chained together.
• Serial ATA: This is a new standard for connecting Hard Drives. The cables are physically much thinner than the old wide IDE cables, and while the transfer speeds are 150MB/s or faster, it is also supposed to be more reliable than the old IDE. Remember, Serial ATA requires Hard Drives to support this feature or you will not be able to connect it.
• Jumperless: Motherboards have jumpers or dip switches that are used for adjusting the system's clock speed. Many computer users will never alter their system's clock speed, but some individuals may want to. Generally these users are interested in overclocking. Overclocking is the practice of increasing the system clock speed in order to run the system bus and CPU at a higher speed than the manufacturer has recommended. Overclocking will void your CPU's warranty, and it could cause serious damage to your entire system, so ZipZoomFly does not recommend it. However, for those interested in overclocking anyway, a jumperless board is handy. Rather than having to open up your case and adjust the jumpers or dip switches by hand, a jumperless board enables a user to adjust clock speed via software.
• Adjustable AGP/PCI Speeds: Again, adjustable AGP and PCI speeds is something that will only be useful for overclockers. When the speed of the system clock is increased, the speed of the AGP and the PCI bus are also automatically increased, which can cause problems. Adjustable AGP and PCI speeds can eliminate those problems.
• CPU and Motherboard Temperature Monitor: Again, for overclockers. One of the primary dangers of overclocking is too much heat. Temperature monitors help overclockers prevent heat problems.

  Conclusion

  Once you have narrowed down your choices to a few motherboards, investigate the chipsets they use. Some chipsets have better reputations than others. In addition, check out what reviewers have to say about the boards in general. A good place to look for reviews is Neoseeker.com. However, take what you read with a grain of salt as your needs and the things the reviewer was testing for may be very different.

  In addition, it's a good idea to purchase a motherboard built by a reputed manufacturer; just like a house, you don't want to build your PC on a poor foundation. Some well-known motherboard manufacturers include Asus, Abit, Intel, Microstar (MSI), Soyo, SuperMicro, Tyan, and Gigabyte.