Mothers and Daughters
Early in the history of the personal computer, the motherboard (also called the mainboard) was little more than a skeleton to which the CPU, chipset, BIOS, and other boards called daughter boards or risers, were attached. The daughter boards contained such peripherals as the drive controllers, input/output controllers, memory banks, and other devices.
Nowadays, virtually all motherboards (or mobo's, to those in the know) integrate these components onto the motherboards themselves. Devices that are included on modern motherboards, but which typically were separate components in earlier PC's, are commonly known by the somewhat oxymoronic term integrated peripherals.
As an aside, some parts that used to be mounted on the motherboard, such as the L2 and L3 CPU caches, are now typically mounted on the processor itself, which greatly increases processing efficiency.
Being able to identify the components on the motherboard is essential to any home computer builder. It's also a great way to
bore impress family and friends: "That's the SATA connector, right there next to the South bridge chipset."
Modern motherboards usually include the following on-board components:
- The CPU socket (or slot, on ancient boards).
- The chipset (divided into two parts commonly called the Northbridge and the Southbridge).
- Memory (RAM) slots.
- Controllers and connections for for the hard drive, floppy drive, and other storage devices. Most boards being manufactured today have only SATA connectors. EIDE drives are rapidly fading into history, and floppy drives are already there.
- The BIOS (Basic Input / Output Services) chip, which basically tells the computer that it's a computer rather than, for example, a cappuccino machine.
- Controllers and connectors for the serial ports, parallel ports, USB ports, and sometimes other interfaces such as SCSI or Firewire ports.
- In most cases, expansion slots that can accommodate aftermarket expansion cards. PCI and PCI-e slots are the most common nowadays, although boards with AGP slots can still be had.
Some motherboards also include on-board audio, video, network, or modem "cards." These are usually built right onto the motherboard (or embedded in the chipset) and are configured through the BIOS setup. But they're commonly called "cards" anyway.
Integrating peripheral components like audio cards and network cards onto the motherboard helps keep the cost of a new computer down by reducing or eliminating the need for add-on cards. The quality of built-in components ranges from awful (on el-cheapo boards), to excellent (on high-end boards).
One downside to built-in cards is that they usually are neither repairable nor upgradeable. That's one reason why most motherboards that feature integrated audio, video, modem, or network interface cards also offer the option to disable the onboard devices and install add-on cards to take their place if the integrated cards should go belly-up or become obsolete.
How, exactly, to disable an onboard device varies from mobo to mobo. Some newer motherboards will sense when an add-on card has been installed and will disable the built-in device automatically. On other boards, you will have to enter BIOS setup and disable the device, usually in the "Integrated Peripherals" menu. And sometimes (especially on older boards), you will have to locate and move a jumper to disable an onboard component.
Non-Windows Operating Systems and Onboard Components
If you are planning to install an operating system other than Windows on your homebuilt computer, bear in mind that most integrated peripherals are designed with Windows in mind. Usually these components will work under Linux or other Unix-based operating systems, but not always. Check the manufacturer's documentation or the hardware newsgroups to make sure the components will work with your OS before you plunk down any money for the board.
Revision date: July 10, 2012