3.3.1-3.3.2.txt

Computer cases come in many different shapes and sizes. Each computer case is designed to fit a specific motherboard size called the form factor. The form factor is a specification that determines the motherboard’s dimensions. It defines the width and height, the locations of mounting holes, back pa...

Computer cases come in many different shapes and sizes. Each computer case is designed to fit a specific motherboard size called the form factor. The form factor is a specification that determines the motherboard’s dimensions. It defines the width and height, the locations of mounting holes, back panel ports, and expansion slots. Having these specifications makes pairing a motherboard with a case extremely easy. If the case has the same form factor as a motherboard, then you know they will be compatible. In this lesson, we’re going to look at the most common form factors and how they affect the size and dimensions of computer cases. Let’s start with the ATX form factor. ATX Form Factor 0:46-1:37 The ATX form factor, also called Standard ATX, is the most commonly used form factor. Standard ATX motherboards are 9.6 inches by 12 inches. While the type and number of ports on the back panel of an ATX motherboard can vary, they need to fit within the ATX form factor’s specified dimensions. The dimensions for the back panel are 6.25 inches by 1.75 inches. Another characteristic of the ATX form factor is the number of expansion slots and their spacing. Standard ATX motherboards have between six and seven expansion slots. These are spaced 0.8 inches apart. There are several variants of the ATX form factor. They are considered variants because they adhere to certain specifications such as mounting hole locations, back panel port arrangement, and expansion slot spacing. However, they have entirely different dimensions. Micro-ATX 1:38-1:52 One variant is the microATX form factor. The typical dimensions of a microATX motherboard are 9.6 inches by 9.6 inches. The reduced length of this form factor is achieved by having only four expansion slots instead of seven. Extended ATX 1:53-2:24 Another variant is the Extended ATX (EATX) form factor. Instead of reducing its size, the EATX form factor adds up to three and a half inches to the Standard ATX form factor. This extra space is used for extra slots for memory modules. Remember, these are all ATX variants. This means that even though they are different sizes, the mounting holes, back panel ports, and expansion slots are all in the same location. If we were to stack all three ATX variants on top of each other, everything would line up. ITX 2:25-3:09 Another common form factor is the ITX form factor. The ITX form factor is primarily used with small form factor computers. There are several variants of the ITX form factor, the most common of which is the mini-ITX form factor. Mini-ITX motherboards measure 6.7 inches by 6.7 inches and have only one expansion slot. They’re pretty small. They were designed to be a low power, low temperature motherboard that could be used in smaller computers. Even though it’s a different form factor than ATX, Mini-ITX was designed so that the mounting holes and back panel arrangement matches the ATX form factor. This allows Mini-ITX motherboards to be used with ATX cases. Other ITX form factors include Nano-ITX, Pico-ITX, and Mobile-ITX. BTX and NLX 3:10-3:51 There are two more form factors we should mention. These form factors are rarely used, but you still might encounter them. The first is the BTX form factor. This form factor was intended to replace the ATX form factor. The BTX form factor has roughly the same dimensions as ATX form factor. However, BTX motherboards have a completely different back panel orientation. The second is the NLX form factor. NLX motherboards use a unique back panel design. They also use what’s called a riser card. This attaches to the motherboard, allowing expansions to be installed parallel to the motherboard. Case Types 3:52-4:17 Now that we’ve looked at all the different motherboard form factors, let’s take a look at how they affect a case’s size and dimensions. Cases are identified by both their type and the form factor they are compatible with. So let’s take a look at the most common types of cases. Computer cases come in all different shapes and sizes. Remember, they are designed to fit a specific motherboard form factor. ATX Full-Tower 4:18-4:39 The ATX full-tower is probably the largest case you’ll see. ATX full-towers are made to be compatible with all ATX form factors, including EATX. Full-tower cases usually have several external bays for things like DVD ROM drives. They also have a lot of room inside the case for hard drives, large graphics cards, and power supplies. ATX Mid-Tower 4:40-4:59 Next is an ATX mid-tower. ATX mid-towers are slightly smaller than ATX full-towers. However, they are still compatible with all the ATX form factors. Some ATX mid-towers are even compatible with the Mini-ITX form factor. ATX mid-towers have fewer external bays. They also have less internal space. Micro-ATX Tower 5:00-5:36 There are two types of microATX towers. The first one is a traditional microATX tower. It has a single external bay and it’s considerably smaller than the ATX mid-tower or full-tower. This second one is a microATX slim tower. These cases can either stand upright or lie flat on a desk. Both of these towers are compatible with the microATX form factor as well as the Mini-ITX form factor. One big difference between these two towers is that due to its slim design, the microATX slim tower requires a riser card to install expansion cards. Mini-ITX Tower 5:37-5:48 The last case is a Mini-ITX tower. These cases are only compatible with the Mini-ITX form factor. Because of this, they are smaller than the microATX towers. Those are the different form factors used by motherboards and cases. Remember, the form factor identifies the dimensions and specifications of a motherboard. It also determines which type of case the motherboard is compatible with. By knowing the different form factors, you can make informed decisions when deciding which motherboard and case will best suit a specific need. And when selecting a case, you need to consider not only the size and the number of external and internal bays, but also the motherboard form factor you are going to use. 3.3.2 Cases and Form Factor Facts Next Resource Motherboard form factor standards help ensure that computer components can be interchangeable among vendors and generations of technology. Knowledge of the form factors are important when you customize and upgrade systems. This lesson covers the following topics: Motherboard form factors Common motherboard form factors Common computer cases Computer case components Motherboard Form Factors Motherboards adhere to design specifications called form factors. The form factor determines the physical characteristics of a motherboard including: Dimensions Power supply type Mounting hole locations Number of expansion slots Back panel Dimensions Arrangement Orientation Common Motherboard Form Factors Form factors evolve slowly in response to changing demands of the computer market. The following graphic and table describe the characteristics of the most common motherboard form factors. Motherboard form factors Form Factor Characteristics Advanced Technology Extended (ATX) The ATX form factor is the most used form factor. Because of its popularity, there are several versions of the ATX form factor. Each version has a different specification for dimension and number of expansion slots. All ATX versions share the following characteristics: Back plate measurements (6.25" × 1.75“) Power supply specifications: 24-pin ATX power connector On/off switch runs from the case to the motherboard Soft-power control (OS can turn the computer off) Expansion slot locations and spacing (0.8” between slots) Mounting hole locations CPU location (top of board near power supply) Below are the most common ATX versions and their unique characteristics. Standard ATX The standard ATX form factor is the form factor that all other versions are modeled after. ATX motherboards: Measure 12" × 9.6" Have up to seven expansion slots Have between six and nine mounting holes Extended ATX (EATX) The EATX form factor is the largest ATX version. EATX: Measures 12" × 13" Typically uses extra space for additional memory slots microATX The microATX form factor is a smaller version of the ATX form factor. The microATX form factor: Measures 9.6" × 9.6" Has four expansion slots Information Technology EXtended (ITX) The ITX form factor was designed for low-power, small form factor (SFF) computers. The most common ITX form factor is the Mini-ITX form factor. Mini-ITX form factor: Specifies a maximum motherboard size of 6.7" × 6.7" Has only one expansion slot Allows for small (100 watt) power supplies Is typically used with a home theater PC (HTPC) Other ITX form factors include the following: Nano-ITX (4.7" × 4.7“) Pico-ITX (3.9” × 2.85“) Mobile-ITX (2.9” × 1.7") The Mini-ITX form factor uses the same mounting locations and back panel specifications as the ATX form factor. This allows Mini-ITX motherboards to fit in ATX cases. New Low Profile Extended (NLX) NLX is an old form factor that was designed for use in slimline desktop computers. NLX form factor: Uses a detachable riser card to provide expansion slots (the motherboard itself has no expansion slots) Allows the motherboard to slide in or out of the system case easily Was replaced by microATX and Mini-ITX Balanced Technology eXtended (BTX) The BTX form factor was designed as a replacement for the ATX form factor. It did not gain widespread adoption. BTX form factor: The CPU is positioned in such a way that air flow is increased. There is no heatsink fan. Instead, a thermal module or shroud fits over the CPU to move heat directly out of the system. The back panel orientation and mounting location is reversed. BTX was implemented mainly by computer manufacturers such as Dell. Common Computer Cases Computer cases are designed to fit motherboard form factors. The following table describes the most common types of computer cases: Type Description ATX full-tower ATX full-tower cases are the largest computer cases. Full-tower cases have a lot of space for external and internal components. ATX full-tower cases are compatible with the following form factors: Standard ATX EATX microATX ATX mid-tower ATX mid-tower cases are slightly smaller than full-tower cases. Mid-tower cases have fewer external and internal bays. ATX mid-tower cases are compatible with the following form factors: Standard ATX microATX Mini-ITX EATX (some) microATX tower microATX towers are smaller cases designed to be placed on desktops. microATX towers typically have only one drive bay. microATX towers are compatible with the following form factors: microATX Mini-ITX Some microATX towers have a slim design. These cases are typically half the width of a microATX tower and are designed to lie flat or upright. Mini-ITX tower Mini-ITX towers are designed to house mini-ITX motherboards. They are typically smaller than microATX towers. Home theatre PC (HTPC) HTPC cases are designed to connect to TVs and be used as a home media computer. HTPC cases are compatible with microATX and Mini-ITX form factors. Notebook Notebook cases are generally proprietary and often vary among models. Some small form factor cases (e.g., microATX and Mini-ITX towers) use riser cards for installing expansion boards. Riser cards are installed in an expansion slot and allow the expansion board to be installed parallel to the motherboard, instead of perpendicular. Computer Case Components When you purchase a computer case, it usually ships with the following components: Computer case. Power supply (although the power supply can be separate). Case fans. Plastic or rubber feet that attach to the bottom of the case. Metal screws and standoffs for attaching the motherboard. Additional external connectors (such as audio, USB, and FireWire) that connect to motherboard headers.