Know and understand characteristics of a desktop computer

1. Types and Components of Computer Systems

1.1 Overview of Computer System Types

Computer systems can be classified according to size, purpose and portability. The main categories are:

• Supercomputers – extremely powerful, used for scientific simulations.
• Mainframe computers – large, multi‑user systems for organisations.
• Servers – provide services to other computers on a network.
• Desktop computers – personal computers designed for use on a desk.
• Laptops and tablets – portable devices with integrated components.
• Embedded systems – specialised computers built into other equipment.

1.2 Focus: Desktop Computer

A desktop computer is a personal computer intended to remain in a fixed location. It typically consists of separate hardware components that can be upgraded or replaced.

1.3 Core Components of a Desktop Computer

Component	Function	Typical Specifications
Central Processing Unit (CPU)	Executes instructions and processes data.	Multi‑core (e.g., 4‑core, 8‑core); clock speed 2.0 – 4.5 GHz
Motherboard	Provides the main circuit board that connects all components.	ATX form factor; supports DDR4/DDR5 RAM; multiple expansion slots
Memory (RAM)	Temporary storage for data being processed.	8 GB – 32 GB; DDR4/DDR5
Storage	Permanent data storage.	HDD 1 TB – 4 TB or SSD 256 GB – 2 TB
Power Supply Unit (PSU)	Converts mains AC to DC power for the computer.	450 W – 750 W; 80 + Gold efficiency
Graphics Processing Unit (GPU)	Renders images, video and 3D graphics.	Integrated or dedicated; VRAM 2 GB – 12 GB
Cooling System	Maintains safe operating temperatures.	Air cooling (fans) or liquid cooling
Case (Chassis)	Protects components and provides airflow.	Mid‑tower, full‑tower, mini‑tower
Input Devices	Allow the user to interact with the computer.	Keyboard, mouse, scanner, webcam
Output Devices	Present information to the user.	Monitor, speakers, printer

1.4 Characteristics of a Desktop Computer

The following characteristics distinguish desktop computers from other types of systems.

1. Modularity – Individual components (CPU, RAM, storage, GPU) are separate and can be upgraded.
2. Performance – Typically higher processing power and larger memory capacity than laptops of comparable price.
3. Power Consumption – Requires a constant mains connection; power draw is usually higher than portable devices.
4. Ergonomics – Allows the use of full‑size keyboards, mice and large monitors, reducing strain during prolonged use.
5. Cost Efficiency – For a given performance level, desktops are generally cheaper than laptops because components are less constrained by size and power.
6. Heat Management – Larger chassis accommodate more effective cooling solutions, enabling higher sustained performance.
7. Connectivity – More expansion slots and ports (USB, HDMI, Ethernet, audio jacks) are available.

1.5 Example Specification Sheet

Below is a typical specification for a mid‑range desktop used in schools.

Specification	Detail
CPU	Intel Core i5‑12400, 6 cores, 2.5 GHz base (up to 4.4 GHz boost)
RAM	16 GB DDR4 3200 MHz (2 × 8 GB)
Storage	512 GB N \cdot Me SSD + 2 TB 7200 RPM HDD
GPU	N \cdot IDIA GeForce GTX 1650, 4 GB GDDR5
Monitor	24‑inch Full HD (1920 × 1080) IPS
Operating System	Windows 11 Education
Power Supply	550 W 80 + Bronze certified

1.6 Performance Considerations (Simple Model)

For a basic estimation of processing capability, the following relationship is often used:

$$\text{Performance} \approx \text{Clock Speed (GHz)} \times \text{Number of Cores}$$

Example: A 3.2 GHz quad‑core CPU would have an estimated performance of $3.2 \times 4 = 12.8$ (arbitrary units).

1.7 Summary

Desktop computers are versatile, high‑performance machines that offer modularity, ergonomic advantages and cost‑effective upgrades. Understanding each component’s role and the overall characteristics helps learners evaluate suitability for different tasks, from classroom learning to more demanding multimedia work.