3.5 Given a scenario, install and configure motherboards, central processing units (CPUs), and add-on cards.
📘CompTIA A+ Core 1 (220-1201)
What Is a Motherboard Form Factor?
A motherboard form factor defines:
- The physical size of the motherboard
- The shape of the motherboard
- The mounting hole locations
- The number of expansion slots
- The type of computer case it can fit into
- The power supply compatibility
In an IT environment, choosing the correct motherboard form factor is critical because:
- The motherboard must fit inside the case
- It must support the required CPU, RAM, and expansion cards
- It affects cooling, expandability, and future upgrades
For the CompTIA A+ exam, you must recognize and compare common motherboard form factors.
Major Motherboard Form Factors You Must Know
1. ATX (Advanced Technology eXtended)
Overview
ATX is the most common standard motherboard form factor used in desktop computers.
Key Characteristics
- Size: 12 × 9.6 inches (30.5 × 24.4 cm)
- Supports multiple expansion cards
- Commonly used in full-size desktop systems
- Designed for maximum expandability
Expansion Slots
- Typically up to 7 expansion slots
- Supports:
- Graphics cards
- Network cards
- Sound cards
- Storage controller cards
Memory and CPU Support
- Supports multiple RAM slots
- Designed for full-size CPUs
- Handles higher power and better cooling
Power Supply
- Uses standard ATX power connectors
- Requires a larger power supply unit (PSU)
IT Environment Usage
- Office desktops
- Workstations
- IT lab systems
- Systems requiring multiple add-on cards
Exam Notes
✔ Most expandable
✔ Largest size
✔ Requires ATX-compatible case
✔ Best for upgrades
2. microATX
Overview
microATX is a smaller version of ATX that balances size and functionality.
Key Characteristics
- Size: 9.6 × 9.6 inches (24.4 × 24.4 cm)
- Designed to reduce cost and space
- Very popular in business and home desktops
Expansion Slots
- Typically up to 4 expansion slots
- Fewer slots than ATX but enough for:
- One graphics card
- Network or sound card
Memory and CPU Support
- Usually supports 2–4 RAM slots
- Uses standard desktop CPUs
- Slightly limited cooling compared to ATX
Power Supply
- Compatible with ATX power supplies
- Fits in smaller cases
IT Environment Usage
- Office computers
- Small business systems
- Standard classroom or training PCs
Exam Notes
✔ Smaller than ATX
✔ Fewer expansion slots
✔ Cost-effective
✔ Fits in many ATX cases
3. ITX (Information Technology eXtended)
CompTIA A+ focuses mainly on Mini-ITX, which is the most common ITX type.
Overview
ITX motherboards are designed for very small computers.
Key Characteristics
- Common size (Mini-ITX): 6.7 × 6.7 inches (17 × 17 cm)
- Very compact design
- Used when space is limited
Expansion Slots
- Typically 1 expansion slot
- Limited ability to add cards
- Often relies on built-in (onboard) components
Memory and CPU Support
- Fewer RAM slots (usually 2)
- Supports low-power CPUs
- Limited cooling options due to small size
Power Supply
- May require:
- Small-form-factor PSUs
- External power adapters (in some designs)
IT Environment Usage
- Small office systems
- Compact desktops
- Kiosk systems
- Embedded or dedicated-function computers
Exam Notes
✔ Smallest size
✔ Very limited expansion
✔ Low power usage
✔ Requires special case and cooling considerations
Comparison Table (Exam-Friendly)
| Feature | ATX | microATX | ITX |
|---|---|---|---|
| Size | Largest | Medium | Smallest |
| Expansion Slots | Up to 7 | Up to 4 | Usually 1 |
| RAM Slots | Many | Moderate | Few |
| Power Usage | High | Medium | Low |
| Expandability | Excellent | Good | Very Limited |
| Common Use | Workstations | Office PCs | Small systems |
Key Exam Points to Remember
✔ Motherboard form factor determines case compatibility
✔ Larger boards = more expansion slots
✔ Smaller boards = less power usage and fewer upgrades
✔ ATX → most expandable
✔ microATX → balance of size and features
✔ ITX → compact, low-power systems
Common Exam Scenarios
You may see questions like:
- Which motherboard fits a small-form-factor case?
- Which form factor supports the most expansion cards?
- Which motherboard is best for limited space?
- Why would an IT technician choose microATX instead of ATX?
Final Exam Tip
For the CompTIA A+ exam:
- Memorize the size order:
ATX → microATX → ITX - Associate bigger size = more expandability
- Associate smaller size = limited upgrades
