What is a Motherboard?

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The Motherboard (also known as the Mainboard, System Board, or Mobo) is the backbone of your system, handling the inter-connection of every component in the PC.  If the CPU is the "brain" of the computer, the motherboard is the spine and nervous system.

What does the Motherboard do?

The job of the motherboard is to handle the connection of devices within your PC and acts as the primary backbone of your build.  Without the motherboard, all you have is a collection of parts that are unable to communicate with one another.  For this job, every motherboard should include the following basic features:

  • A CPU Socket or integrated CPU
  • RAM slots or integrated DRAM
  • Power Connectors
  • Expansion Slots
    • These are generally PCIe or M.2, however some motherboards may include specialized slots

In addition to the basics above, many motherboards will come with additional integrated features that help reduce the number of add-in cards your system will need in order to function.  These features include, but are not limited to:

  • Network Interface Controller (NIC)
    • Ethernet and Wifi are the most common, while some motherboards may feature specialized connectors.
  • Bluetooth Controller
  • USB Controller
  • Storage Controller (SATA, U.2, etc.)
  • Audio Interface (Sound Card)
  • Display Controller (may require a supported CPU)

The ATX Standard & Motherboard Form Factor

For the purposes of this article, we will be putting a focus on the ATX Standard and its derivatives, as these are the most common form factors used in building a PC.

Motherboard-Form-Factor-Map.png

The above map shows a breakdown of the four most common motherboard form factors and their screw placements.  In particular, mATX (in Red) and E-ATX (in Blue) may need additional or adjusted standoffs.

Short for Advanced Technology Extended, ATX is a motherboard, case, and power supply specification patented at Intel as an improvement of the previous Advanced Technology (AT) standard.  This standard is a set of rules governing the design, layout, and compatibility of various PC parts.  This includes definitions of the dimensions, mounting points, I/O panels, and power and connector interfaces across PC products to ensure compatibility.  The ATX standard also spun off various standards such as microATX (mATX), FlexATX, Extended ATX (E-ATX), and the popular mini-ITX standard for small form factor PCs.

ATX

The most common form factor and the namesake of the standard itself, the dimensions of a full-size ATX motherboard is 12 x 9.6 inches or 305 x 244 mm with a total of 9 standoff mounts divided across the top, middle, and bottom row of the motherboard.  Some ATX motherboards may be slightly wider to accommodate additional components or slightly narrower and not require the furthest right row of standoffs.

mATX

Micro ATX or mATX is a popular standard for smaller form factor PCs, trading expandability for a more compact size.  The stnadard mATX size is 9.6 x 9.x6 inches or 244 x 244 mm, however some mATX motherboards may be slightly shorter or slightly wider depending on the manufacturer.  For standoff placement, the top and middle row standoffs are shared with the ATX standard but some adjustment may be necessary for the bottom row.  For more information, please refer to your motherboard user's manual.

mini-ITX

While not explicitly a part of the ATX standard, mini-ITX is a popular form factor for ultra-compact PCs.  This standard makes a further trade of expandability for its compact size, coming in even smaller than the mATX standard at an impressive 6.7 x 6.7 inches or 170 x 170 mm and requiring only 4 standoffs located at the four corners of the motherboard.

EATX

Extended ATX or E-ATX is seen as a bigger version of the ATX standard, measuring at up to 12 x 13 inches or 305 x 330 mm.  These motherboards are primarily aimed at Enthusiast and Workstation motherboards, sometimes including support for multiple CPUs, more RAM slots, or more full-length expansion slots as well as specialized hardware.  It is worth noting however that while some E-ATX motherboards may be compatible with the ATX mounting pattern, some boards are explicitly not compatible with ATX mounting.  For more information, please refer to your motherboard and case user's manuals.

There is also a commonly used subset of E-ATX motherboards with a width of between 10 and 10.9 inches which shares the same hole mounting compatible with ATX.

What is the CPU Socket?

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The CPU Socket is the bridge that connects the CPU to the Motherboard.  CPU Sockets come in many different sizes but primarily only one of two types:  Land-grid Array (LGA) and Pin-grid Array (PGA).

Land-grid Array or LGA sockets feature pins in the socket itself that make contact with pads on the underside of the CPU.  These are most common across Intel CPUs as well as newer AMD CPUs like the AM5 Socket and various TR based sockets like TR4 and sTR5.

Pin-grid Array or PGA sockets feature pins on the underside of the CPU which slot into the motherboard socket.  This type of socket is most common with AMD CPUs prior to AM5, including the AM4 and AM3 series of sockets.

What is a Chipset?

The Motherboard Chipset is the component of the motherboard that acts as an intermediary between the CPU and the various hardware of the motherboard.  For Intel based systems, this is referred to as the Platform Controller Hub (PCH) while for AMD based systems it is simply referred to as a Chipset.  The Chipset's job is to govern the connection between certain data paths and support functions for the CPU including controlling the system clock, providing additional connectivity for PCIe devices, and acting as the connection point for various peripheral connections such as USB, SATA, NICs, etc.

Your motherboard may also have various features depending on the type of chipset being used, such as Intel's Z series chipset including the ability to adjust clock speeds and timings for unlocked K-series processors which are not found on their B and H series counterparts.

What is an Expansion Slot?

Expansion Slots are what allow your motherboard to connect to and accept Expansion Cards to give additional functionality to your PC.  The most common types of Expansion Slots are PCIe and M.2.

PCI Express (PCIe)

Short for Peripheral Component Interconnect Express, PCIe is a standard introduced in 2003 that allows you to easily add expansion cards such as Graphics Cards, Capture Cards, Storage, Network Controllers, and various other hardware to your PC.

PCIE-Slot-Types.png

PCIe slots come in a variety of sizes based on the number of lanes utilized by the card ranging from x1 to x16.  It is worth noting that any expansion card will work with a slot with equal to or more lanes (i.e. you can install a x1 or x4 card into a x8 or x16 slot).

Checkpoint - PCIe Lanes and Slots

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Some PCIe devices or slots on motherboards may appear to be x16 but may be wired for less lanes like x8 or x4.  For more information, please refer to your motherboard or device's motherboard manual.

M.2

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Formerly known as Next Generation Form Factor (NGFF) is a specification for internally mounted expansion cards.  M.2 is primarily used for smaller expansion cards such as Network Controllers and SSDs.  Most motherboards will feature the M.2 "M-Key" connector, while some older motherboards may feature the older "B-Key" connector.  It is worth noting however that M-Key and B-Key devices are not physically compatible with one another.

What is the Rear I/O?

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The Rear I/O is the part of the motherboard you will likely be interacting with the most directly.  Your Rear I/O is a collection of outside-facing ports, buttons, and switches that will normally face the rear of the PC case.  This collection includes USB ports, Ethernet Ports, 3.5mm Audio jacks, and in some cases even buttons to reset the UEFI BIOS or power on the PC.

How do I pick a motherboard for my build?

When picking a motherboard, the first thing you'll need to check is that your motherboard is compatible with the CPU you have chosen.  For example, an LGA 1700 Socket motherboard will only be compatible with LGA 1700 Socket CPUs and will not be compatible with LGA 1156 Processors or AMD AM5 Processors despite all three processors being compatible with LGA sockets.

When checking CPU compatibility, most motherboard manufacturers will have a CPU Compatibility Guide either as part of the manual or on the product's web page.  This will not only tell you which CPUs are physically compatible, but will include information as to if a BIOS update may be required to use newer CPUs of the same socket.

Next you will want to consider the case you are planning to use for your build.  For example, if you are going with a mid-tower case such as the popular NZXT H5it may be better go to with a full-size ATX motherboard rather than an ITX motherboard which may have less features and cost more overall.  Likewise, a larger format ATX or E-ATX motherboard may not fit in more compact cases.

Finally, consider the features that you will want or need for your PC.  This can include various integrated features such as the performance of the Network Interface Controller (NIC), number of M.2 Slots or PCIe slots, or additional features such as the ability to use Wifi or debugging features that may help in the event of a crash or failed startup.

Lastly, your choice in motherboard will have a major effect on the features available to your PC.  This can include things such as the performance of your Network Interface Controller (NIC), number of M.2 and PCIe slots, or even grant extra features such as the ability to use Wifi or Bluetooth.  When picking your motherboard, these features 

For example, let's take a look at two generic motherboards:

Motherboard One Motherboard Two

B650 Chipset
4 RAM Slots
Debug LEDs
2.5G LAN
4 M.2 NVMe Slots

B650 Chipset
4 RAM Slots
1G LAN
3 M.2 NVMe Slots
Integrated Wifi + Bluetooth
Price:  $180 USD Price:  $180 USD

Comparing the two motherboards above, we can see that the price is the same for the sam echipset but there are some key feature differences.  Motherboard One has a better NIC for wired Ethernet as well as an additional NVMe Slot for more storage and Debug LEDs in case you need to troubleshoot an issue.  Motherboard Two has a weaker NIC for wired Ethernet, has less expandability and lacks debug LEDs, but does come with an integrated Wifi and Bluetooth controller.

Motherboard One may be a better fit for someone with a dedicated wired Ethernet connection, but if you're in a place where you'll be relying on Wifi such as a college dorm or apartment that lacks a hardline connection then Motherboard Two may be the better fit.

A few nice to have features on a motherboard include, but are not limited to:

  • Integrated Wifi + Bluetooth
  • Debug LEDs or Post Code Display
  • Optical S/PDIF aka TOSLINK Audio
  • USB 3.1 Gen 2 Type-C

Does my Motherboard have an effect on my PC's performance?

A question you may be asking is does my choice of motherboard affect the performance of my PC?  In many cases, the answer will be no, the motherboard will have little to no impact on PC performance.

The exception to this rule is if you are looking at motherboards capable of overclocking.  If you are using an Unlocked CPU with an Overclocking oriented motherboard, there are features such as the number of power phases and specific BIOS features that may help improve performance.

Do you have any questions not covered by this guide or need further assistance?  Please feel free to reach out to our Customer Support team and one of our friendly support agents will be there to assist you.

Are you looking to keep up on all things NZXT?  Go ahead and join the Official NZXT Community Discord to keep up to date on our latest products, upcoming sales, and join in on discussions on everything from PC hardware to gaming.

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