Motherboards, CPUs & Power Supplies
Key Takeaways
- ATX (305 x 244 mm) is the standard desktop board; Micro-ATX (244 x 244 mm) and Mini-ITX (170 x 170 mm) are the smaller form factors, and a smaller board always fits a larger case.
- Intel uses LGA sockets (pins on the board); AMD used PGA on AM4 but moved to LGA on AM5 — match the CPU socket to the motherboard exactly.
- PSU wattage must exceed total component draw with 20–30% headroom; 80 Plus ratings (Bronze through Titanium) certify efficiency.
- The 24-pin connector powers the board, the 8-pin EPS/ATX12V powers the CPU, and PCIe 6+2 or 12VHPWR connectors power the GPU.
- Secure Boot, TPM 2.0, and enabled virtualization (VT-x / AMD-V) are UEFI settings the exam ties to Windows 11 and VM support.
Motherboard Form Factors
| Form Factor | Dimensions | Expansion Slots | RAM Slots | Use Case |
|---|---|---|---|---|
| ATX | 305 x 244 mm | up to 7 | 4 | Standard desktops, gaming |
| 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, HTPCs |
| Extended ATX (EATX) | 305 x 330 mm | 7+ | 8 | Workstations, servers |
Exam Tip: A smaller board mounts in a larger case (Mini-ITX in an ATX case), but a larger board never fits a smaller case. Cases and boards share the same mounting-hole standard, so the rule is one-directional.
Motherboard Components
Expansion Slots (PCI Express)
| Slot | Lanes | Typical Use |
|---|---|---|
| PCIe x16 | 16 | Graphics cards, high-bandwidth add-ins |
| PCIe x8 | 8 | RAID/HBA cards, second GPU |
| PCIe x4 | 4 | NVMe add-in cards, 10GbE NICs |
| PCIe x1 | 1 | Sound cards, basic NICs, USB cards |
| M.2 (M key) | 4 (PCIe) | NVMe SSDs |
PCIe is backward and forward compatible: a x1 card works in a x16 slot, and a x16 card runs (at reduced bandwidth) in an open-ended x4 slot. Each generation doubles per-lane bandwidth — Gen 4 x16 is ~32 GB/s, Gen 5 x16 is ~64 GB/s.
BIOS / UEFI Key Concepts
| Feature | BIOS (Legacy) | UEFI (Modern) |
|---|---|---|
| Interface | Text, keyboard only | Graphical, mouse + keyboard |
| Boot disk size | up to 2.2 TB (MBR) | over 2.2 TB (GPT) |
| Secure Boot | Not supported | Supported |
| Network boot | Limited | Full PXE |
High-yield UEFI settings:
- Boot order — selects first boot device
- Secure Boot — blocks unsigned bootloaders/drivers
- TPM 2.0 — hardware key store; required for Windows 11 and BitLocker
- Virtualization (VT-x / AMD-V) — must be ON for Hyper-V/VMs
- XMP / EXPO — applies rated RAM speed profiles
- Fan curves and a supervisor/BIOS password for security
CPU (Central Processing Unit)
Current Intel vs. AMD Platforms
| Spec | Intel (current) | AMD (current) |
|---|---|---|
| Socket | LGA 1700 / LGA 1851 | AM5 |
| Pin location | LGA — pins on board | LGA — pins on board (AM5) |
| Chipsets | Z790, B760 / 800-series | X670E, B650, A620 |
| RAM | DDR4 or DDR5 (board-dependent) | DDR5 only (AM5) |
Exam Tip: The previous AMD AM4 socket was PGA (pins on the CPU), so a bent CPU pin was the AMD failure mode; Intel LGA and AMD AM5 put the delicate pins in the socket. Always match socket family — an AM5 chip will not fit AM4.
Specs to know
- Cores / Threads — physical units vs. logical via Hyper-Threading/SMT (usually 2 threads per core)
- Clock speed (GHz) and boost clock
- Cache — L1 fastest/smallest, L3 largest/shared
- TDP — Thermal Design Power in watts; sizes the cooler
- Integrated graphics — Intel UHD or AMD Radeon iGPU when present
CPU Cooling
| Cooler Type | Description | Approx. TDP |
|---|---|---|
| Stock cooler | Bundled heatsink + fan | up to 65W |
| Tower air cooler | Heatpipes + large fin stack | 65–250W |
| AIO liquid cooler | Sealed pump, radiator, fans | 100–350W |
| Custom loop | User-built water cooling | 200W+ |
Important: Apply a thin, even layer of thermal paste (a pea-sized dot) between the CPU integrated heat spreader and the cooler base. Without it, microscopic air gaps trap heat and the CPU thermally throttles or shuts down. Too much paste insulates and can short pins if it overflows.
Power Supply Unit (PSU)
Power Connectors
| Connector | Purpose | Pins |
|---|---|---|
| ATX Main | Motherboard power | 24-pin |
| EPS / ATX12V | CPU power | 4+4 (8-pin) |
| PCIe | GPU power | 6-pin, 6+2, or 12VHPWR (16-pin) |
| SATA power | SSD/HDD | 15-pin |
| Molex | Legacy fans/peripherals | 4-pin |
80 Plus Efficiency (at 50% load)
| Rating | Efficiency |
|---|---|
| 80 Plus | 80% |
| Bronze | 85% |
| Silver | 88% |
| Gold | 90% |
| Platinum | 92% |
| Titanium | 94% |
Sizing the PSU
Rule: total component draw + 20–30% headroom. Headroom keeps the unit in its efficient band and leaves room for upgrades and capacitor aging.
| System Type | Recommended PSU |
|---|---|
| Basic office PC | 300–450W |
| Mid-range gaming | 550–750W |
| High-end gaming | 750–1000W |
| Workstation | 850–1200W |
Other PSU facts
- Modular (fully detachable cables) aids cable management vs. non-modular.
- A failing PSU shows random reboots, no power, burning smell, or POST beeps — swap with a known-good unit or test with a PSU tester/multimeter.
- Verify the voltage selector switch (115V/230V) matches the region; setting 115V hardware to a 230V outlet causes catastrophic failure.
- Never open a PSU — capacitors hold lethal charge even unplugged.
Which motherboard form factor measures 170 x 170 mm and typically provides a single expansion slot?
A technician must enable a feature so a workstation can run Hyper-V virtual machines. Which UEFI setting is required?
A user upgrading from an AMD AM4 system reports the new Ryzen CPU will not seat in the board. What is the underlying cause?
The substance applied between a CPU and its heatsink to fill microscopic gaps and improve heat transfer is called _______ paste.
Type your answer below