Motherboards, CPUs & Power Supplies
Key Takeaways
- ATX (305 x 244 mm) is the standard desktop motherboard size, while Micro-ATX (244 x 244 mm) and Mini-ITX (170 x 170 mm) are smaller form factors for compact builds.
- Modern CPUs use either an LGA (Land Grid Array — pins on motherboard) or PGA (Pin Grid Array — pins on CPU) socket; Intel uses LGA, AMD uses both PGA (AM4) and LGA (AM5).
- The CPU socket must match the motherboard — Intel LGA 1700 (12th/13th/14th Gen) and AMD AM5 (Ryzen 7000+) are current-generation sockets.
- Power supply wattage must exceed the total power draw of all components with 20-30% headroom; the 80 Plus certification (Bronze, Silver, Gold, Platinum, Titanium) rates power efficiency.
- The 24-pin ATX connector provides main power to the motherboard, the 8-pin EPS/ATX12V provides CPU power, and PCIe 6+2 pin connectors provide power to dedicated graphics cards.
Last updated: March 2026
Motherboards, CPUs & Power Supplies
Motherboard Form Factors
| Form Factor | Dimensions | Expansion Slots | RAM Slots | Use Case |
|---|---|---|---|---|
| ATX | 305 x 244 mm | Up to 7 | 4 (typically) | Standard desktops, gaming, workstations |
| Micro-ATX (mATX) | 244 x 244 mm | Up to 4 | 2–4 | Budget/compact desktops |
| Mini-ITX | 170 x 170 mm | 1 | 2 | Small form factor (SFF), HTPCs |
| Extended ATX (EATX) | 305 x 330 mm | Up to 7+ | 8 | High-end workstations, servers |
Exam Tip: Smaller motherboards are backward-compatible with larger cases. A Micro-ATX board fits in an ATX case, but an ATX board does NOT fit in a Micro-ATX case.
Motherboard Components
Expansion Slots
| Slot Type | Bandwidth | Use Case |
|---|---|---|
| PCIe x16 | Up to 64 GB/s (Gen 5) | Graphics cards, high-speed expansion |
| PCIe x4 | Up to 16 GB/s (Gen 5) | NVMe SSDs, RAID controllers |
| PCIe x1 | Up to 4 GB/s (Gen 5) | Sound cards, network cards, USB expansion |
| M.2 | Varies by key | NVMe SSDs, Wi-Fi cards |
Rear I/O Panel (Typical)
| Port | Purpose |
|---|---|
| USB-A 3.x | Peripherals, storage devices (blue ports) |
| USB-C | Modern peripherals, displays |
| HDMI / DisplayPort | Video output (integrated graphics) |
| RJ-45 (Ethernet) | Wired network (1 Gbps or 2.5 Gbps) |
| 3.5mm Audio | Speakers, microphone, line-in |
| PS/2 | Legacy keyboard/mouse (purple = keyboard, green = mouse) |
BIOS/UEFI Key Concepts
| Feature | BIOS (Legacy) | UEFI (Modern) |
|---|---|---|
| Interface | Text-based, keyboard only | Graphical, mouse + keyboard |
| Boot Drive Size | Up to 2.2 TB (MBR) | Over 2.2 TB (GPT) |
| Boot Speed | Slower | Faster |
| Secure Boot | Not supported | Supported (validates boot software) |
| Network Boot | Limited | Full PXE support |
Common BIOS/UEFI Settings:
- Boot Order — Determines which device boots first (SSD, USB, network)
- Secure Boot — Prevents loading of unauthorized operating systems and drivers
- Virtualization (VT-x / AMD-V) — Must be enabled for virtual machines
- TPM — Trusted Platform Module for hardware-based encryption (required for Windows 11)
- Fan Control — Adjusts fan curves for cooling management
- XMP/EXPO — Enables RAM speeds beyond base specifications
CPU (Central Processing Unit)
Intel vs. AMD Current Platforms
| Specification | Intel (Current) | AMD (Current) |
|---|---|---|
| Socket | LGA 1700 | AM5 |
| Pin Type | LGA (pins on motherboard) | LGA (pins on motherboard) |
| Chipsets | Z790, B760, H770 | X670E, B650, A620 |
| RAM Support | DDR4 or DDR5 (board dependent) | DDR5 only (AM5) |
| PCIe | Gen 5 (CPU lanes) | Gen 5 (CPU lanes) |
CPU Specifications to Know
| Specification | Description |
|---|---|
| Cores | Number of processing units (more = better multitasking) |
| Threads | Virtual cores via hyperthreading/SMT (typically 2 threads per core) |
| Clock Speed | Measured in GHz — higher = faster per-core performance |
| Cache | L1 (fastest, smallest), L2 (medium), L3 (largest, shared between cores) |
| TDP | Thermal Design Power — maximum heat output in watts (determines cooler size) |
| Integrated Graphics | Some CPUs include a built-in GPU (Intel UHD, AMD Radeon) |
CPU Cooling
| Cooler Type | Description | TDP Rating |
|---|---|---|
| Stock Cooler | Included with CPU, basic aluminum heatsink + fan | Up to 65W |
| Tower Air Cooler | Large heatsink with heatpipes and fan(s) | 65–250W |
| AIO Liquid Cooler | Closed-loop water cooling with radiator | 100–350W |
| Custom Loop | Open-loop water cooling (user-assembled) | 200W+ |
Important: Always apply thermal paste between the CPU and cooler. Without thermal paste, the CPU will overheat and may be damaged. A thin, even layer (pea-sized dot in center) is recommended.
Power Supply Unit (PSU)
Power Connectors
| Connector | Purpose | Pins |
|---|---|---|
| ATX Main | Primary motherboard power | 24-pin |
| EPS / ATX12V | CPU power | 4+4 pin (8-pin total) |
| PCIe | Graphics card power | 6-pin, 6+2 pin (8-pin), 12VHPWR (16-pin) |
| SATA Power | SATA drives (SSD/HDD) | 15-pin SATA |
| Molex | Legacy peripherals, fans | 4-pin |
80 Plus Efficiency Ratings
| Rating | Efficiency at 50% Load |
|---|---|
| 80 Plus | 80% |
| 80 Plus Bronze | 85% |
| 80 Plus Silver | 88% |
| 80 Plus Gold | 90% |
| 80 Plus Platinum | 92% |
| 80 Plus Titanium | 94% |
PSU Selection
Wattage Formula: Total component power draw + 20–30% headroom
| System Type | Recommended PSU |
|---|---|
| Basic Office PC | 300–450W |
| Mid-Range Gaming | 550–750W |
| High-End Gaming | 750–1000W |
| Workstation | 850–1200W |
Modular vs. Non-Modular
| Type | Description | Benefit |
|---|---|---|
| Non-Modular | All cables permanently attached | Cheapest option |
| Semi-Modular | Main cables attached, others detachable | Good balance of price and cable management |
| Fully Modular | All cables detachable | Best cable management, easiest to build with |
Test Your Knowledge
Which motherboard form factor measures 170 x 170 mm and has only one expansion slot?
A
B
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D
Test Your Knowledge
What power connector supplies dedicated power to the CPU on a modern motherboard?
A
B
C
D
Test Your Knowledge
A user is building a gaming PC and selects a power supply rated 80 Plus Gold. What is the minimum efficiency at 50% load?
A
B
C
D
Test Your KnowledgeFill in the Blank
The substance applied between a CPU and its heatsink to improve heat transfer is called _______ paste.
Type your answer below