Computer Components: Motherboard, Processor, and RAM

Posted on Sep 28, 2024 in Electronics

Item 3: Components Inside Your Computer

3.1 Motherboard

The motherboard, also known as the mainboard, is the central component of a computer. It connects almost all devices, enabling them to function correctly. The motherboard determines the computer’s capacity, compatible components, and potential for future expansion.

The motherboard is made of synthetic material with printed circuits, a set of chips, and various connectors and sockets.

Factors and Motherboard Shapes:

  • AT: Designed by IBM for XT computers. It’s the first standard size, measuring 12×13.2 inches.
  • Baby AT: Smaller than AT due to higher component integration. Used in PCs from the 286 to Pentium era.
  • ATX: Created by Intel and the most popular. Improved component placement with CPU and memory near the fan. It has a single power connector, and drive connectors are closer to the CPU.
  • Mini-ATX: A compact version of ATX with the same component layout.
  • MicroATX: Even smaller than Mini-ATX, fully compatible with ATX cases (introduced in 1997).
  • LPX: Used in many brand-name desktops. Integrated peripherals are common (e.g., sound card, video card, modem). It incorporates the riser card, a special connector for expansion cards.
  • NLX: Similar to LPX but allows tool-less removal and replacement of components.
  • BTX: (2004) Developed by Intel to address CPU heat issues. Components are placed differently than in ATX to improve airflow. The CPU is positioned directly below the fan, but other components are out of the direct airflow. This model hasn’t been successful due to space limitations.
  • WTX: Created by Intel in 1998 for servers with multiple CPUs and hard drives.

3.2 Motherboard Components

Components found on the motherboard:

  • Microprocessor socket
  • Memory slots (DIMM or SIMM)
  • Chipsets (Northbridge, Southbridge)
  • BIOS
  • Expansion slots (PCI, AGP, PCI Express)
  • External I/O connectors (PS/2, serial, parallel, USB, LAN, S/PDIF, audio, FireWire, VGA, DVI, joystick)
  • Internal connectors (IDE, SATA, PATA, USB, floppy drive, CD-IN, fan, SPDIF)
  • Power connectors (ATX, ATX 12V)
  • Motherboard battery

3.3 The Processor

As discussed in Item 2, the processor is the computer’s brain, directing and controlling all operations. Physically, it’s a chip with millions of transistors on a silicon wafer. Its size varies depending on the device (computer, PDA, mobile phone).

Older processors were soldered to the motherboard, making them difficult to replace. Although processors had a long lifespan, their evolution was slow. Today, processors connect to a socket, allowing for upgrades as technology advances.

a. Internal Architecture

Processor evolution involves integrating more components onto a single chip, making them faster and more powerful. However, the fastest processor isn’t always the best choice. A knowledgeable user should select a processor based on capacity, price, and intended application.

Modern buses with speeds of 6 GHz are crucial for operating systems like Vista or 7 and for real-time video decompression.

Current CPU Block Diagram

Early microprocessors had basic components (ALU, registers) as described by Von Neumann architecture. Each CPU evolution incorporated new features for increased speed and power.

Modern CPUs use dual-core or quad-core architectures with up to four separate processors, each with its own resources. This architecture enables simultaneous multimedia applications.

The goal is parallel processing, where each core handles specific tasks without affecting others.

Dual-core architecture incorporates features like:

  • FPU (floating-point unit)
  • Level 1, 2, and 3 cache
  • Front-side bus (FSB)
  • DDR memory controller
  • High-bandwidth transport bus

3.3.b Processor Features

Speed

Measured in MHz or GHz (1000 MHz = 1 GHz). There are two types of speed:

  • Internal: The speed at which the internal bus operates.
  • External or System Bus: The FSB speed is slower than the internal speed and represents the speed at which the CPU communicates with the motherboard.

The multiplier indicates the difference between the CPU speed and the FSB speed.

Example: A Pentium IV with a speed of 2.6 GHz and a 500 MHz bus has a multiplier of 5.2 (2600 MHz / 500 MHz = 5.2).

Cache Memory

A memory layer between the CPU and RAM. It’s slower than the CPU but much faster than RAM, although smaller. It stores frequently accessed data. Cache memory is organized into levels (L1, L2, L3). L1 is closest to the CPU, fastest, and smallest. Higher levels have more capacity but are slower.

L1 is often divided into two parts: one for instructions and one for data. When buying a CPU, the cache is usually specified as follows:

  • 64 KB + 64 KB (64 KB for data and 64 KB for instructions)
  • 2 x 5 MB (two levels, each with 5 MB of cache)
  • 2 MB (total cache shared across all levels)
Power Supply

The microprocessor receives power from the motherboard. There are two types of voltage:

  • External: Allows the CPU to communicate with other components (usually 3.3V).
  • Internal: Used for internal communication within the CPU (typically lower than the external voltage, often 2.4V to 1.8V).
TDP (Thermal Design Power)

The maximum amount of heat that the computer’s cooling system needs to dissipate. A CPU with a TDP of 20W requires fans and heatsinks that can handle that amount of heat. Without proper cooling, the CPU can overheat and get damaged.

Special Instructions

These instructions are designed to improve performance in multimedia applications by creating efficient instructions. They are used for tasks like real-time video decompression (MPEG-2, MPEG-4).

Each processor generation adds new instruction sets to enhance performance. Intel started with MMX instructions, and AMD introduced 3DNow! instructions. Modern processors use SSE4 and beyond.

c. 32-bit and 64-bit Architectures

The terms 32-bit, 64-bit, or 128-bit refer to the width of the ALU registers, address bus, and data bus.

32-bit architectures are suitable for applications with smaller data sets. They have a maximum addressable memory limit of 4 GB. 64-bit architectures can address much larger memory spaces and handle larger data sets.

While 64-bit computers are becoming more common, many applications still run in 32-bit mode.

3.4 RAM

RAM (Random Access Memory) is the primary memory that stores data readily accessible by the CPU. There are different types of memory for quick access:

  • RAM: The main memory where data can be read or written quickly. It’s volatile (data is lost when the computer is turned off). Current capacities range from 1 GB to 4 GB and beyond.
  • Cache: Memory closest to the CPU, faster than RAM but smaller. It stores frequently used data and is organized into levels (L1, L2, L3).
  • CMOS: Stores the computer’s hardware configuration data. It can be modified.
  • ROM: Stores the computer’s boot sequence. It’s non-volatile but can be updated.
  • Graphics Memory (VRAM): Located on the graphics card, it’s used for graphics processing to offload the RAM. Modern graphics cards have dedicated memory, often in GBs. Laptops typically share graphics memory with the main RAM.

RAM Parameters

  • Speed: Measured in MHz or GHz. It represents the number of operations per second.
  • Bandwidth: The amount of data that can be transferred per second (measured in MB/s or GB/s).
  • Dual Channel: Allows parallel access to memory modules, requiring identical modules (same type, capacity, and speed).
  • Latency: The time it takes to find requested data in memory.
  • CAS Latency (CL): Latency measured in clock cycles.
  • Access Time: The time it takes to access the memory itself (measured in nanoseconds).
  • ECC (Error Correction Code): A system for detecting and correcting memory errors. It identifies and sometimes repairs errors.

Types of RAM

  • SRAM (Static RAM): Retains information as long as power is supplied. It’s made of transistors, occupies more space, has lower capacity, and is faster than DRAM. Used for cache memory.
  • DRAM (Dynamic RAM): Needs to be constantly refreshed. It’s made of capacitors and is more compact and less expensive than SRAM. Used in personal computers.
  • VRAM (Video RAM): Adapted for graphics cards, often based on SRAM but with modifications for cost-effectiveness.
  • SDRAM (Synchronous DRAM): Uses a clock to synchronize read and write operations. It operates in burst mode and is commonly used with a 64-bit bus and speeds of 100 or 133 MHz.
  • DDR SDRAM (Double Data Rate SDRAM): Allows parallel operations, doubling the bandwidth. Operates at speeds up to 200 or 266 MHz.
  • DDR2 SDRAM: An evolution of DDR with improved speed and lower voltage (reducing heat). Speeds reach 400 MHz, and module capacity is up to 2 GB. The downside is increased latency.
  • DDR3 SDRAM: Further evolution with higher speed, lower power consumption, and module capacities up to 8 GB. Latency is further increased.

Advantages and Disadvantages of DDR3 Compared to DDR2:

Advantages: Higher speed, higher capacity, lower voltage, less heat.

Disadvantage: Higher latency.

Memory Modules

Memory modules are small printed circuit boards containing multiple memory chips.

General-Purpose Memory Modules

  • SIMM: Older memory modules, now obsolete. Used in computers from the 1980s and 1990s.
  • DIMM: 168-pin modules with two notches. Used for SDRAM with capacities from 32 MB to 2 GB.
  • DDR DIMM: 184-pin modules with one notch in the center. Used for DDR SDRAM.
  • DDR2 DIMM: 240-pin modules with a notch in the center (different position than DDR DIMM). Used for DDR2 SDRAM.
  • DDR3 DIMM: 240-pin modules with a notch in the center (different position than DDR2 DIMM). Used for DDR3 SDRAM.
  • RIMM: Modules with 168 to 232 pins. Much faster than previous types and often have heatsinks. They are expensive and used for RDRAM memory.

Special-Purpose Memory Modules

  • FB-DIMM: 240-pin modules with a notch in a different position than DDR3 DIMM. Used for servers. They are very fast but generate a lot of heat, have higher latencies, and are expensive.
  • GDDR: Integrated graphics memory, especially for gaming. Very fast and controlled by the graphics card processor. Based on DDR SDRAM technology.
  • SODIMM: Small-size memory for laptops, using SDRAM technologies.
  • MicroDIMM: Even smaller than SODIMM, for DDR and DDR2, but not compatible with SODIMM.
  • Buffered Modules: Act as a buffer between the CPU and main memory, improving data reliability but increasing transfer times. Used in servers.
  • Unbuffered Modules: Connect directly to the Northbridge, making them faster but less secure.