Motherboard Types


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  Step 1:  Understanding ATX Motherboards

The most common motherboard designs in use today are based on the ATX design. ATX motherboards always have a two-row port cluster on the rear of the motherboard which is covered with a removable plate (see figure option A). When viewed from the rear, an ATX system's power supply is at the left (B), and its expansion slots are at the right (C). A full-size ATX motherboard can have as many as seven expansion slots, but most have five or six. ATX tower cases are opened from the left-hand side.
  Step 2:  Understanding MicroATX/FlexATX

MicroATX and FlexATX are reduced-size versions of ATX, using the same overall layout (see Step 1), but with fewer expansion slots, fewer memory sockets and a smaller overall design (see figure). MicroATX motherboards, used in low-cost retail systems, have three or four slots. FlexATX motherboards are smaller, typically have two, one or no slots; they are used in small-form-factor and low-profile systems.
  Step 3:  Introducing BTX

The newest form factor is BTX (Balanced Technology Extended), introduced in 2004. BTX cases are opened from the right-hand side (see figure). BTX systems use in-line airflow (red arrows), larger fans and a thermal module for the processor to provide more effective cooling than ATX. Other differences include a larger port cluster and a 24-pin power connector. Thus, a BTX motherboard requires a different case design than an ATX motherboard.
  Step 4:  Small Form Factor

Many systems on the market today are labeled "small form factor" (SFF). Some vendors of SFF systems use the FlexATX or the similar Mini-ITX/micro-FlexATX motherboard designs, enabling motherboard upgrades and easy repairs. Others use proprietary designs. If you are considering purchasing an SFF system and are considering its upgradeability, be sure to determine if the system uses a standard or proprietary motherboard design.
  Step 5:  Obsolete Form Factors

Open a Report
The following motherboard form factors are obsolete: AT, Baby-AT, LPX, and NLX. Baby-AT motherboards, a reduced-size version of the AT form factor, were common until the late 1990s. Most ports were on add-on cards or used header cables on expansion slots covers. LPX motherboards, sold until the mid-1990s, have a single row of ports on the rear edge and used various types of riser cards for expansion slots. NLX systems (late 1990s) used a standardized riser card and a quick-release motherboard design for fast replacement.