Motherboards: ATX, mATX, ITX, Oh my!

Picking the right motherboard size and understanding them:

Motherboards are the unsung heroes of computing, GPUs and CPUs get all the glory of delivering high frame rates, or massive computational power, but the seemingly innocuous motherboard is what makes the magic happen. The motherboard is the set of devices, interfaces and controllers on a PCB (Printed Circuit Board) that allows all the parts of your computer to communicate. The main parts are as follows:

CPU Socket:

A set of either pins or contacts, usually gold that allows for a connection between the CPU (Central Processing Unit) and the rest of the computer. This forms the core of the motherboard.

Power Delivery:

Delivered through several sets of power connectors from the PSU (Power Supply Unit). These are referred to by their pin count and what they deliver power to. For example, a connector for CPU power with 2×4 pins would be called an 8-pin CPU connector, whereas the 2×12 pin connector going throughout the motherboard would be the 24-pin ATX connector.

RAM Slots:

The number, type and channel of your motherboard’s RAM will be very important to getting the most out of your system. Typically, RAM is in sets of two or four, and are classified by their speed and capacity. This will be discussed in more depth in the RAM section of the article. The important thing to note here, is that you are buying a motherboard that matches with your RAM. This will mean getting the right capacity and type, primarily.


The SATA Bus is the controller that allows your CPU to access storage on devices connected to it. The most common storage solutions are some sort of SATA drive. SATA devices are classified by their generation and correspond to their speed. Modern SATA III devices are capable of a theoretical 6Gb/s per second, and modern motherboards support SATA III as well. The main thing to look for is going to be how many drives it supports, and if your workflow requires it, RAID support.

PCIe Lanes:

PCIe or Peripheral Component Interconnect Express is the interface that many high-bandwidth components like GPUs, NICs (Network Interface Cards) or other similar devices. These are classified by their generation and number of lanes. Modern PCIe lanes are Generation 3, or Gen 3 and come in x1 lanes, x4, x8 and x16 varieties. For example, a NIC may be listed as requiring PCIe 3.0 x1, which means that it can fit in any slot, but it will only use the 1x lane. Ideally, you should have all of the devices in matching PCIe lanes. A note should be made that you can put a smaller lane in a larger one, but not the other way around. This means that while a x1 device will fit in an x16, but an x16 will not fit in anything smaller.

So, in review, the most important connections you’ll need to look for in a motherboard are the CPU socket, the RAM, SATA bus and PCIe connections. Next, we’ll move on to sizes of motherboards.

The main sizes of motherboard are ATX, mATX and mITX. There are others, like EATX or Extended ATX or manufacturer specific boards for servers, and small, integrated devices like cash registers but the main ones are going to be the three listed above. Let’s break them down from largest to smallest.

ATX motherboards are the largest boards commonly used and are going to have the most interfaces for storage, RAM, PCIe devices and have the best power delivery, chipset and frequently are the flashiest looking boards. Cases are typically sized by their motherboard compatibility and most full and mid-tower cases are going to fit an ATX board.

mATX or Micro ATX motherboards are the smaller cousins of the ATX board, and frequently have the same chipset, power delivery and much of the same device interfaces, usually at the cost of PCIe slots and some extra connectors here and there. These boards are a good fit for mid-tower cases as well as home and office computers that need a bit more power than normal. The boards will typically fit in any ATX case, as they use a lot of the same fasteners.

mITX or Mini ITX boards are the smallest boards of this set and will frequently have lower end chip sets, though some are running much the same parts as a mATX or ATX board, will have fewer PCIe slots, SATA connectors and RAM slots. These boards are best for small, low profile builds, home and office computers and mid to entry range gaming machines.

While this can be quite a bit of information to sift through at first, much of the compatibility, expansion capabilities and sizes are handled for you through our PC customization tools.

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