Difference Between Micro ATX and Mini ITX

Micro ATX vs Mini ITX

Mini-ITX and micro-ATX are desktop computer form factors. They define the specific nature of the dimension, power requirements and supply, peripheral connector/add-ons and connector types of the computer system. It primarily concerns the configuration of the motherboard, the power supply unit and the chassis of the computer system.

Micro ATX

Micro ATX, also referred to as uATX, mATX, or µATX, is a standard introduced in 1997 based on the ATX specification. ATX is a specification standard of motherboards created by the Intel corporation in 1995 as an advancement from the AT standard. ATX stands for Advanced Technology eXtended. It was the first major change made to the hardware configuration of desktop type computers.

The ATX specification defines the mechanical dimensions, mounting points, Input/ Output panel power and connector interfaces between the motherboard, power supply, and the chassis. With the new specification, interchangeability was introduced in many components of the hardware, in desktop computers. The general microATX board has a dimension of 244 x 244 mm.

ATX standard introduced the capability to use a separate section of the system for add-ons and extensions for the motherboard, and it is often called the Input/ output panel, which is the panel at the back of the chassis and used to connect devices. The configuration of the I/O panel is set by the manufacturer, but the standard allows ease of access which was not present in the earlier AT configuration. These features are inherent in the newer micro ATX systems, as well.

ATX also introduced PS2 mini-DIN connectors for connecting keyboards and mouse to the motherboards. 25 pin parallel port and RS- 232 serial port were the predominant form of peripheral connectors in the early ATX motherboards. Later, the Universal Serial Bus (USB) connectors have replaced the above connectors. Also Ethernet, FireWire, eSATA, audio ports (both analog and S/PDIF), video (analog D-sub, DVI, HDMI) are installed in the newer versions of the ATX motherboards. The micro ATX can be considered as a derivative of the ATX standard. The mounting points are the same; hence allows micro ATX motherboards to be compatible with the chassis of a standard ATX system board. The main I/O panel and the power connectors are the same, allowing peripherals and devices to be interchangeable. However, the number of connectors present in a microATX board is lower than a standard ATX board.

The power supply used in microATX systems is same as the one used in ATX. The power supply unit has three main output voltages at +3.3 V, +5 V, and +12 V. Additional Low-power −12 V and a 5 V standby voltage are also available. The power is connected to the motherboard using a 20 connector, which is designed to reduce accidental incorrect connections that may lead to irrecoverable damages. It also gives a +3.3V supply directly and removes the requirement that 3.3V be derived from the 5V supply.


Mini-ITX is a form factor of low power motherboards developed by VIA technologies in 2001 and is commonly used in small form factor computer architectures.

The mini-ITX (mITX) based computers offer performance comparable to similar architectures with lower power usage. Mini-ITX motherboards have the same mounting holes as ATX, making the boards capable to be installed in chassis designed for standard or MicroATX motherboards. They have lesser number of expansion slots than the microATX motherboard. However, making lesser noise compared to other systems makes it ideal for smaller and quiet computer systems. Therefore, they are often used as home theatre PC`s.

Earlier, the mITX used EPIA 5000 and EPIA 800 processors, which are also manufactured by VIA technologies. However, now other manufacturers have accepted the mITX and both Intel and AMD processors support the mITX architecture.

Mini ITX vs Micro ATX

• Micro ATX is a form factor specification developed by the Intel Corporation based on the ATX specification. Mini-ITX is developed by the VIA technologies.

• Mini ITX is smaller than the micro ATX.

• mITX have only one PCIE expansion slot while micro ITX has more than one expansion slot, but fewer than a standard ATX system.

• Mini-ITX makes lesser noise compared to microATX based computers.