Motherboard Definition

motherboard (sometimes alternatively known as the main circuit boardsystem boardbaseboardplanar board or logic boardor colloquially, a mobo) is the main printed circuit board (PCB) found in general purpose microcomputers and other expandable systems. It holds and allows communication between many of the crucial electronic components of a system, such as the central processing unit (CPU) and memory, and provides connectors for other peripherals. Unlike a backplane, a motherboard usually contains significant sub-systems such as the central processor, the chipset’s input/output and memory controllers, interface connectors, and other components integrated for general purpose use and applications.

Motherboard specifically refers to a PCB with expansion capability and as the name suggests, this board is often referred to as the “mother” of all components attached to it, which often include peripherals, interface cards, and daughtercards: sound cards, video cards, network cards, hard drives, or other forms of persistent storage; TV tuner cards, cards providing extra USB or FireWire slots and a variety of other custom components.

Similarly, the term mainboard is applied to devices with a single board and no additional expansions or capability, such as controlling boards in laser printers, televisions, washing machines and other embedded systems with limited expansion abilities.


Types of Motherboard:

 

AT Motherboard

An AT motherboard is a motherboard which has dimensions of the order of some hundred millimeters, big enough to be unable to fit in mini desktops. The dimensions of this motherboard make it difficult for the new drives to get installed. The concept of six pin plugs and sockets is used so as to work as the power connectors for this type of motherboards.

The hard to distinguish power connector sockets make it difficult for many users to easily make the proper connections and thus leading to the damage of the device.

Produced in the mid 80’s, this motherboard lasted a good span from the Pentium p5 to the times when Pentium 2 had been started to be used.

ATX Motherboard

Advanced technology extended, or popularly known as the ATX, are the motherboards which were produced by the Intel in mid 90’s as an improvement from the previously working motherboards such as AT.

This type of motherboards differ from their AT counterparts in the way that these motherboards allow the interchangeability of the connected parts. Moreover the dimensions of this motherboard are smaller than the AT motherboards and thus proper place for the drive bays is also allowed.

Some good changes were also made to the connector system of the board. The AT motherboards had a keyboard connector and on the back plates extra slots were provided for various add-ons.

LPX Motherboard

The low profile extension motherboards, better known as LPX motherboards, were created after the AT boards in the 90’s.

The major difference between these and previous boards is that the input and output ports in these boards are present at the back of the system. This concept proved to be beneficial and was also adopted by the AT boards in their newer versions. The use of a riser card was also made for the placement of some more slots. But these riser cards also posed a problem that the air flow was not  proper.

Also, some low quality LPX boards didn’t even have real AGP slot and simply connected to the PCI bus. All these unfavored aspects led to the extinction of this motherboard system and was succeeded by the NLX.

BTX Motherboard

BTX stands for Balanced Technology extended.

BTX was developed to reduce or avoid some of the issues that came up while using latest technologies. Newer technologies often demand more power and they also release more heat when implemented on motherboards in accordance with the circa-1996 ATX specification. The ATX standard and the BTX standard, both were proposed by Intel. The further development of BTX retail products was canceled in September 2006 by Intel after the acceptance of Intel’s decision to focus again on low-power CPUs after suffering issues such as scaling and thermal with the Pentium 4.

The first company to use, or to be precise, implement BTX was Gateway Inc, followed by Dell and MPC. Apple’s MacPro uses only some of the elements of the BTX design system but it is not BTX compliant. This type of motherboard has some improvements over previous technologies:

  • Low-profile – With the larger demand for ever-smaller systems, a redesigned backplane that shaves inches off the height requirements is a benefit to system integrators and enterprises which use rack mounts or blade servers.
  • Thermal design – The BTX design provides a straighter path of airflow with lesser difficulties, which results in better overall cooling capabilities. Instead of a dedicated cooling fan, a large 12 cm case-fan is mounted, that draws its air directly from outside the computer and then cools the CPU through an air duct. Another feature of BTX is the vertical mounting of the motherboard on the left-hand side. This kind of feature results in the graphics card heat sink or fan facing upwards, rather than in the direction of the adjacent expansion card.
  • Structural design – The BTX standard specifies distinct locations for hardware mounting points and hence reduces latency between key components. It also reduces the physical strain imposed on the motherboard by heat sinks, capacitors and other components which are dealing with electrical and thermal regulation.

Pico BTX Motherboard

Pico BTX is a motherboard form factor that is meant to manufacture even smaller size BTX standard. This is smaller than many current “micro” sized motherboards, hence the name “Pico” has been used. These motherboards share a common top half with the other sizes in the BTX line, but they support only one or two expansion slots, designed for half-height or riser-card applications.

In the initial stages of usage, the ATX and BTX motherboards were so analogous that moving a BTX motherboard to an ATX case was possible and vice-versa. At later stages, the BTX form factor had a large modification which was done by turning it into a mirror image of the ATX standard. Technically speaking, BTX motherboards are ‘left side-right’ when compared to ATX and not upside-down as before. This means they are mounted on the opposite side of the case. Various computer cases for instance, the Cooler Master Series (Stackers) were released to support a wide range of motherboard standards such as ATX, BTX, Mini-ATX and so on, in order to simplify motherboard development without buying a new case; however, all connector and slot standards are identical, including PCI(e) cards, processors, RAM, hard drives, etc.

BTX power supply units can be exchanged with latest ATX12V units, but not with older ATX power supplies that don’t have the extra 4-pin 12V connector.

Mini ITX Motherboard

Mini-ITX is a 17 × 17 cm (6.7 × 6.7 in) low-power motherboard form factor. It was designed by VIA Technologies in year 2001. These are largely used in small form factor (SFF) computer systems. Mini-ITX boards can also be cooled easily because of their low power consumption architecture. Such an architecture makes them widely useful for home theater PC systems or systems where fan noise can diminish the quality or worth of cinema experience. The four mounting holes in a Mini-ITX board line up with the four holes in ATX specification motherboards, and the locations of the back plate and expansion slot are the same. Although, one of the holes used was optional in earlier versions of the ATX. Hence, Mini-ITX boards can be used in places which are designed for ATX, micro-ATX and other ATX variants if required.

The Mini-ITX form factor has location for one expansion slot, pertaining to a standard 33 MHz 5V 32-bit PCI slot. However, often case designs use riser cards and some even have two-slot riser cards, even when the two-slot riser cards are not usable with all the boards. A few boards based around non-x86 processors have a 3.3V PCI slot, and the Mini-ITX 2.0 (2008) boards have a PCI-express ×16 slot. Such boards are not used with the standard PCI riser cards supplied with cases.

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