Motherboard

Updated: 2021-02-21

Factors to Consider

Socket

The motherboard should have the correct socket for the CPU you choose.

  • AMD: AM4 sockets for all mainstream chips (Ryzen, Athlons)
  • Intel:

    • 10th Gen: LGA 1200 socket
    • 9th Gen: LGA 1151v2 socket

Chipset

The chipset on the motherboard decides which CPU can be installed, how many PCIe / USB (and which versions)s can be supported, etc.

Naming conventions:

  • AMD: X for Enthusiast (e.g. X570), B for Performance (e.g. B550), A for Mainstream (e.g. A520)
  • Intel: X for Extreme, Z for Performance, H for Mainstream, B/Q for Budget

Form Factor

ATX (Advanced Technology eXtended) is the de facto standard for PCs. However it comes in different sizes:

(Standard) ATX > Micro-ATX > Mini-ITX > Nano-ITX > Pico-ITX > Mobile-ITX

  • ATX is the most common one; usually 4 RAM slots
  • Micro-ATX has the same width with ATX but shorter, so it just offers less expansion slot.
  • Mini-ITX: for tiny PCs, only one card slot. Note that it is "ITX" (Information Technology eXtended) instead of "ATX"

The smaller the board, the fewer PCIe / RAM slots. Also you need to pay attention to the tower specs, make sure the motherboard can fit in.

RAM Slots and Expansion Slots

The standard ATX motherboards usually offer 4 RAM slots.

The expansion slots come in different sizes, modern motherboards usually have the followings:

  • PCIe x1 slots: short ones
  • PCIe x16 slots: longer ones, for graphic cards
  • M.2 connector: for NVMe SSDs; up to 4 PCIe lanes

Ports (I/O)

  • USB: pay attention to the USB versions
  • HDMI / DisplayPort: if you plan to use GPU, these are NOT needed
  • Audio ports
  • Ethernet ports

Other considerations

  • some motherboard has built-in Wi-Fi

Background Knowledge

Northbridge vs Southbridge

  • northbridge, or host bridge / Memory Controller Hub, is directly connected to the CPU vis frontside bus(FSB), while southbridge is not.
  • The northbridge was directly responsible for communications with high-speed devices (system memory and primary expansion buses, such as PCIe, AGP and PCI cards, being common examples) and conversely any system communication back to the processor. The southbridge handled "everything else", generally lower-speed peripherals and board functions (the largest being hard disk and storage connectivity) such as USB, parallel and serial communications.
  • Requests to resources not directly controlled by the northbridge were offloaded to the southbridge, with the northbridge being an intermediary between the processor and the southbridge.
  • The connection between the northbridge and southbridge was normally the PCI bus

PCI Express

PCI stands for Peripheral Component Interconnect.

PCIe, or PCI Express, uses a serial, lane-based architecture; it replaces the older PCI, which uses a shared parallel bus architecture.

PCIe slot sizes: x1, x2, x4, x8 or x16. A smaller card can plug in a larger slot, not vice versa.