Computer case

The computer case is designed to protect the computer's internal components from external influences and mechanical damage. It is also used to maintain the required temperature inside and to shield the electromagnetic radiation generated by the internal components.

Front side of the computer case

On the front side of the computer case, there are the following:

• Buttons for switching on and rebooting the computer;
• Headphone and microphone sockets;
• USB ports for the connection of external devices.

Back side of the computer case

Main connectors on the back of the case:

• PS sockets for keyboard (green) and mouse (purple).
• 5mm sound card connectors. Green - line output, Blue - line input, Pink - microphone output.
• USB connectors in quantity from 4 to 8 pieces.
• Connector for fibre optic internet connection.
• The VGA, DVI, HDMI, Displayport ports are used for connecting a monitor.

Optional connectors may be included:

• Game connector for connecting a joystick or music synthesizer;
• Parallel port for the connection of various peripherals, e.g. a printer.

In addition to the connectors, plugs are also provided on the backside of the case.

These blanking caps allow video and sound cards to be plugged into the back of the chassis. They can be disposable or detachable, depending on the chassis manufacturers.

Form Factor

Monoblock Computer

The computer consists of a motherboard and a monitor assembled into a single unit. There is no standard size in this form factor version. Manufacturers determine all sizes.

Vertical cases

1 – Slim tower

2 – Mini tower

3 – Midi tower

4 – Full tower

Slim-tower

It is a miniature case by size. It lacks upgradability due to the closeness of all computer components to each other.

The motherboard form factor is Micro-ATX and Mini-ATX.

Dimensions: Width 112 mm x Depth 300 mm x Height 400 mm.

Mini-tower

This case supports Micro-ATX and Mini-ATX motherboards.

Dimensions: Width 178 mm x Depth 432 mm x Height 432 mm.

Midi-tower

This is the most common form factor of the computer system unit. The dimensions allow you to install almost any motherboard, CPU heatsink, fan, and the required number of expansion boards and drives. This type of case supports the ATX motherboard (Standart-ATX) and any compatible motherboards.

Dimensions: Width 180 mm to 250 mm x Depth 430 mm to 450 mm x Height 490 mm.

Full-tower

Due to its large size any motherboard, E-ATX, and XL-ATX server boards can be placed inside. The case capacity allows you to place many drives, fans, liquid cooling systems, expansion cards, etc.

Dimensions: Width from 190 mm x Depth 482 mm x Height 820 mm.

Super-Tower и Ultra-Tower

The largest of the vertical system unit layouts. Most often used as the basis for servers, high-performance workstations, and so on.

These types of cases are available in different sizes depending on the manufacturer's preferences.

Horizontal cases

This type of case has only a horizontal design. It supports the Standart-ATX and smaller form factor motherboards.

Dimensions: Width from 533 mm x Depth from 419 mm x Height from 152 mm.

The other horizontal cases have the following standard dimensions:

• FootPrint (406x406x152);
• SlimLine (406x406x101);
• UltraSlimLine (381 × 352 × 75).

Computer cooling system

Any part of a computer that consumes energy generates heat.

The heat sink is an assembly of cooling systems consisting of a series of thin tubes and reservoirs. It is required to dissipate the heat from the element being heated into the atmosphere. The air passing through the heat sink absorbs the heat.

Heat capacity is the amount of heat released (absorbed) by an object during heating (cooling).

Thermal conductivity is the ability of a material to conduct energy from the more heated parts to the less heated parts.

Heat sinks are made of thermally conductive materials with a minimum heat capacity. Heat sinks must absorb heat quickly and release it quickly. This principle is used to cool any system that transmits heat during operation.

Parts of the motherboard that become very hot during operation are equipped with heat sinks. This includes, for example, the chipset and CPU.

The power supply circuit contains heat sinks

Chipset (Southbridge) radiator

Types of computer cooling systems

Air-cooling

CPU heat sink

A heat sink is fitted to the processor through a special heat-conducting paste. A fan drives a large volume of air through the aluminum grid, and the heat is dissipated with great efficiency.  

Standardized heat sinks and cooling fans are used to cool the CPU.

Air-cooling system in a PC unit and in a laptop

Specially designed cooling stands are available for gaming laptops.

If the enclosure is insufficiently ventilated, the fans in the system unit will drive hot air around in a circle. The heated air will not absorb the heat efficiently. As a result, the heat energy accumulated in the enclosure of the system unit will cause the system to overheat. Overheating may cause the system to burn out or cause some computer components to malfunction.

Liquid cooling system

This cooling system is more expensive to use and more complex to install in the system unit. A liquid cooling system is installed in premium gaming computers. On average, this system provides better heat dissipation than standard air cooling.  

Components of the system:

1. Ventilator
2. Heat sink to dissipate the heat received from the liquid.
3. A heat sink (water block) is a device that draws heat from the system elements to be cooled. The heat sink transfers the heat to the liquid.
4. Pump for circulating liquid. The pump can be combined with a heat sink.
5. Liquid reservoir - this element is necessary to compensate for the thermal expansion of the liquid, easy filling, and draining of the liquid.
6. Hoses or pipes required to move fluid flow between system components.

A liquid flow detector can be fitted.

The liquid that is used is distilled water, often with additives that have a bactericidal or antigalvanic effect.

Some waterblocks, combined with a pump, have a display that shows temperature, fan rotation speed, frequency, voltages, and other parameters.

Classification of liquid cooling systems

A maintained liquid cooling system is a set of individual cooling system components. The pump and water block are separate. This system can be retrofitted, i.e., an additional water block for the graphics card can be installed, the pipes can be lengthened, the heatsink or the liquid can be replaced if required. This system is more complex to install than a maintenance-free liquid cooling system. In addition, there is a risk of leakage and liquid contamination.

A maintenance-free system is a set of ready-to-use sealed systems with liquid filler. The system consists of a combined waterblock and pump, one or more ventilators, tubes, and heatsink. Easy to install. There are no system upgrades or liquid changes.  

Freon cooling systems

The system consists of a compressor, condenser, evaporator, dryer, and capillary tube.

The principle of operation of this cooling system is the same as that of a domestic refrigerator or air conditioner. A refrigerant, Freon, is pumped through the system. The Freon cycle is based on the Joule-Thomson effect. This effect consists of lowering the refrigerant's temperature as its pressure decreases as it flows through a constriction in the tube ducts.

The temperatures obtained with this cooling system are below zero. Due to condensate formation, it is necessary to insulate the cold part of the system.

These cooling systems are very complex to produce and install. In freon systems, it isn't easy to cool several computer components.

Water chillers

These are systems that combine a liquid cooling system with a freon unit. The principle of this system is to cool the antifreeze circulating through the system using a freon unit in a unique heat exchanger. These systems allow low-temperature cooling of several computer components.

The disadvantages of this system include the complexity of installation, the high cost, and the need for thermal insulation of the entire cooling system.

Open-type cooling systems

These units use dry ice, liquid nitrogen, or helium as a refrigerant. The refrigerant is evaporated in a special sealed container mounted on the cooling element. This type of cooling is for those who engage in extreme overclocking. This cooling system has a limited operating time and requires constant refrigerant replenishment.

Sound Card

This is an internal hardware codec (chipset) on the motherboard or a separate expansion card that provides input or output of audio to and from the computer. It is possible to hear the sound through data output devices.

Digital to analog converter

All modern audio recording formats use digital output. Data on CDs, Blu-ray, mp3 files are stored digitally.

Sound cards use a digital-analog converter to convert a digital code (binary) into an analog signal. The analog signal consists of current, voltage, and charge. The signal comes out through a data output device (audio speakers or headphones). 

The analog-to-digital converter is required to convert analog sound (e.g. from a microphone) received by the PC into digital sound.

Types of sound cards

• Internal sound card. This type of sound card is integrated into your computer's motherboard.

• Discrete sound card.

An internal sound card is installed in PCI or PCIe slots. This sound card features an interface in various sound output and input ports on the back of the computer chassis. Depending on the case structure, the ports can be on the sides and at the top of the case.

• External sound device.

External sound cards are necessary to enhance the quality of the output audio. They can be used when the integrated sound card has failed. They are usually connected to your computer via a USB port.

• Mobile sound card

This is a feature-rich device for music lovers. It consists of input and output ports, headphone jacks, and volume control. It can be connected to a computer via PCI and PCIe and FireWire, USB, etc.

Sound card components

1 - Audio RAM. The memory, which includes the primary data for accelerated processing of the data coming to the data card;

2 - Power supply system of the sound card;

3 - Connectors for connecting various devices;

Sound card connectors

1. 3.5mm jack for center channel or subwoofer line out;
2. 3.5mm jack for line-level audio output;
3. 3.5mm jack for microphone audio input;
4. 3.5mm jack for the line-level audio output of the main stereo signal (front sound speakers or headphones);
5. 3.5mm jack for surround sound audio output of the side speakers;
6. Game port - MIDI 15-pin connector for additional audio devices such as synthesizers.

Optical disc drive

This is an electromechanical device intended to read and write information from and to optical discs using a laser.

How it works

There is a spindle electric motor in the middle of the drive which rotates the drive and a drive lever with a read/write head for reading or writing data.

A SATA connector is used to connect the optical drive.

It is a plastic case that houses the laser system. There are two copper coils next to the case. These coils are used to create a magnetic field that allows the laser unit to float above the surface of the disk.

The laser diode and sensors for reading, writing, and deleting data are hidden under the lens.

Drive Classification

• CD-ROM drive reads CDs only;
• CD-RW drive write to CD-R/RW discs only;
• DVD-ROM drive is for reading DVDs;
• DVD/CD-RW drive is the same as DVD-ROM but can record on CD-R/RW discs (combo-drive);
• DVD-RW drive is a drive that is able not only to read DVDs but also to write to them;
• DVD-RW DL drive can burn dual-layer optical DVD media;
• Blu-ray drive (BD-ROM). This is an advanced optical media technology that is based on the use of a 405-nanometer violet laser. These discs are designed to record high-resolution digital video. For example, a single-sided single-layer disc can record up to 2 hours of HDTV video at video streaming rates of up to 54 Mbps;
• BD-RE drive reads and writes to Blu-ray discs;
• HD DVD drive is a new generation of optical discs, which are designed primarily for storing high-definition movies (HDTV). The new media format allows you to record three times as much data as a DVD. Single-layer HD DVDs have a capacity of 15GB and dual-layer discs have a capacity of 30GB. Generally, an HD DVD drive can read all DVD and CD formats;
• HD DVD-ROM drive reads HD DVDs;
• HD DVD/DVD-RW drive able to record and read such disc formats as DVD-R, DVD+R, DVD-RW, DVD+RW, CD-R, CD-RW;
• GD-ROM drive;
• UMD drive;
• DVD-RW drive that supports M-DISC recording can only record M-DISC of the DVD format, and BD-RE drive that supports M-DISC recording can record M-DISC of DVD and Blue Ray formats.

Graphics card

A graphics card (graphics adapter) is a device that is responsible for delivering processed data to the monitor screen as a graphic image.

A graphics card consists of a board with chips, coolers, and connectors. It is installed in the computer case.

Types of graphics cards

• Discrete Graphics Card

This is a board that is installed in an available PCI or PCIe slot on the motherboard.

• Integrated Graphics Card

CPUs can be equipped with a graphics core. The built-in graphics core is suitable for daily office work, surfing the Internet, and watching movies. But for visually complex applications, it will not be sufficient.

• External Graphics Card

It is connected via Thunderbolt or USB connector to your computer or laptop.

Graphics card performance

1. The computer's CPU streams data to the graphics card.
2. The graphics card runs the necessary calculations and processing.
3. The graphics card outputs a pixel-by-pixel graphic image to the monitor screen.

Powerful graphics cards and high-resolution monitors display better, smoother, and more detailed graphics.

Component parts

Parts of the graphics card:

1. 6-pin and 8-pin auxiliary power connectors.
2. The GPU power system and VRAM (Video Random Access Memory).

VRAM is a dedicated memory that the graphics processor uses to store and access pixels and other graphics data.

3. VRAM chips.
4. The graphics processing unit (GPU).
5. An interface connector for connecting to a PCIe slot.
6. SLI connector. This connector allows combining graphics cards in SLI or Crossfire mode (optional).
7. Connectors for image output to the monitor.
8. Connectors for the graphics card cooling system.
9. The video card cooling system consists of a heatsink and fan.

Connector for graphics cards to connect to the motherboard

All modern graphics cards use a PCI-Express x16 connector. The graphics card receives 16 interface data delivery lines from the processor. In addition to data transfer, the PCIe connector also supplies power to the graphics card.

Auxiliary power connectors will be used if the PCIe connector cannot provide full capacity to the graphics card. For this purpose, the graphics card takes extra power directly from the power supply. Modern graphics cards contain from one to several connectors with six or eight pins to connect the wire from the power supply.

Video Memory

Graphics cards come with a specific amount of VRAM, which varies depending on the model of GPU used.

GDDR (Graphics Double Data Rate) is a type of volatile random access memory (DRAM) with a double data rate (DDR). GDDR differs from DDR SDRAM (e.g., DDR3 SDRAM) by its higher-rated frequencies. GDDR has lower power consumption.

The GDDR generations used in modern graphics cards are GDDR5, GDDR6, and GDDR6X.

Video memory is used during image processing. Therefore, the higher the image's resolution, the more video memory is required. The recommended video memory capacity for modern computers is 6 GB.

Cooling System

The cooling system of modern graphics cards consists of several fans and a heatsink.

The heatsink is a device to absorb and dissipate heat from the graphics processor, memory chips, and power elements of the power supply system. The heatsink is made of several sections and plates, combined with several heat pipes.

Fans are used to dissipate heat from the heatsink. The fans can turn off when the temperature of the graphics chip is low.

Power Supply Unit

A power supply unit is a device that converts AC voltage to DC voltage for connecting a computer or a computer server.

Power supplies for desktops provide output ranging from 300W to more than 1,000W.

Application

One of the main functions of a power supply is to convert the current from AC to DC (rectification). Besides driving the computer, the power supply also performs the function of stabilization and protection against minor disturbances in the supply voltage circuit.

Motherboard Compatibility

The power supply can be:

With soldered wires

Modular

If the power supply with soldered wires does not adapt to the motherboard, you can use an adapter.

A modular power supply is a more expensive option than a standard power supply, but it has a lot of great advantages:

• It is possible to change and use the cable that fits your motherboard without adapters.
• No extra wires are hanging; they do not need to be hidden and tied up. This positively affects the air circulation inside the case.
• You can choose the length of the cables.
• Less unnecessary cables reduce the amount of dust in the PC case.

The form factor of commercially available power supplies

1 - The classic ATX standard power supply. It is the most common typical power supply. Dimensions: Height 86mm, Width 150mm, Depth 140mm.

2 - SFX power supply. It is suitable for small computers. SFX can be installed with a special adapter in the ATX case. Dimensions: Height 51,5mm, Width 125mm, Depth 100mm.

3 - TFX power supply. It can be used in small height or special design chassis. Dimensions: Height 65 mm, Width 85 mm, Depth 175 mm.

4 - Flex-ATX power supply. It is a solution for compact desktop systems and servers. Dimensions: Height 40,5 mm, Width 81,5 mm, Depth 150 mm.

5 - Laptop power supply.

What's inside

AC/220 means alternating current 220 volts. It is the connector for the power supply.

Many electrical devices in homes, offices are constantly turning on and off. This can cause voltage fluctuations in the mains. The power supply balances out the input voltage.

The power supply includes input filters. These are capacitors that absorb voltage surges.

The power supply converts the AC input voltage into a DC voltage of 12V, 5V, and 3.3V.

A kind of power supply

1 - Rectifier bridge;

2 - Capacitors;

3 - Pulse width modulator;

4 - Step-down transformer to 12V;

4.2 - Step-down transformer to 5V;

5 - Aluminum heatsink for low voltage diodes.

Output connectors

Each output connector includes two wires: for example, one for the +5 V and a second ground wire for potential equalization. These two wires make a loop: from the power supply to the consumer device and then back to the power supply.

The main connector is a 24-pin ATX12V. This connector provides the main power with several pins of different voltages and several special pins. One of the special connectors is the "+5 standby" output.  This connector provides standby power for the computer. Standby power is required for the motherboard to stay active.

Most power supplies also have an 8-pin connector for the motherboard with two +12V lines and at least one 6-pin or 8-pin PCI Express connector. The difference between the 6-pin and 8-pin PCI Express connectors is two extra ground wires. It allows for more current for high-powered graphics cards.

The Serial ATA (SATA) connector is used to supply power to hard drives, solid-state drives, and DVD drives.

The AMP Mate-N-LOK power connector supplies one +12V, +5V output each, and two ground wires.

Random Access Memory

Random Access Memory (RAM) is the part of a computer memory system that stores executable machine code, input data, output data, and intermediate data processed by the processor.

RAM is a volatile part of the computer memory system. The data contained in semiconductor RAM is accessible and stored only when voltage is applied to the memory modules. If the RAM power is turned off, the stored information in the RAM will be lost.

Types of RAM

There are two types of RAM:

• (SRAM) Static memory is an array of triggers.

A trigger is a device that can be in one of two stable states. It switches from one state to another under the influence of an input signal. The active parts of triggers are transistors and logic gates. A group of transistors and logic gates in a trigger occupies more space than a dynamic memory (DRAM) cell.

Static memory is faster than dynamic memory. Therefore, this type of memory is used to build a cache memory inside the microprocessor.

• (DRAM) Dynamic memory consists of an array of capacitors.

A capacitor is a device for accumulating an electric field charge.

A transistor is a semiconductor component that can drive current in the output circuit from a small input signal. It makes it possible to use it to amplify, switch, and convert electrical signals.

Dynamic memory gets its name from the fact that the capacitor charge gradually decreases over time. A single-bit memory cell consists of a capacitor and a transistor. The capacitor can be charged to a high voltage (logic 1) or a low voltage (logic 0). The transistor acts as a key that connects the capacitor to the control circuitry. The control circuitry allows the capacitor charge state to be read or changed. The density of dynamic memory is higher than static memory. This allows more memory cells to be placed on the silicon chip area of dynamic memory modules.

DRAM is slower than SRAM. This is because a capacitor needs to be charged or discharged to change its state. Recharging the capacitor takes more time than switching the trigger.  To avoid losing the contents of the memory, the capacitor charge value is periodically regenerated through a time called the regeneration cycle. The regeneration procedure is performed by the memory controller.

Main memory functionality

The data exchange between the processor and RAM takes place using cache memory. The cache memory is managed by a special controller, which studies the running program and analyzes which data may be necessary for the processor in the nearest future. These data are loaded from the main memory to the cache memory in advance and returned, already modified by the processor.

RAM - a device that implements the functions of operating memory. RAM may be located on the same chip as the processor, or be a separate external module.  The RAM contains programs, operating system data, user application programs, and the associated program data.

When you turn on the computer, the necessary drivers, special programs, and operating system elements are written to the RAM. Then, the applications and programs to be run by the user are written to RAM.

To retain the contents of RAM, the operating system saves the contents of RAM to a permanent storage device (hard disk drive or solid-state drive) before shutting down the computer.

The number of tasks the computer can perform at one time varies depending on the amount of RAM available.

Interaction scheme between the RAM and the CPU

1 - Processor;

2 - Cache controller;

3 - Cache memory;

4 - RAM;

5 - Paging file.

In case the RAM cells are insufficient, the swap file gets to work. This file is located on a hard disk or SSD. The swap file keeps a record of information that cannot be stored in the RAM cells. The swap file slows down the system considerably since the swap file is slower than RAM.

What is inside a memory module

1. The board on which the module components are mounted;
2. Memory chips;
3. SPD (Serial Presence Detect) - the chip where the basic settings of the module are stored. When you turn on the system BIOS of the motherboard reads the SPD information and sets the time and frequency of RAM;
4. Key - This is a special slot on the board which identifies the module type. This slot prevents the board from incorrectly installing into the RAM slot;
5. SMD module components (resistors, capacitors). These components provide power control of the chips.

More about DRAM

DRAM memory modules are widely used in computers as operational memory devices.

DRAM is a memory module of a standard design. It consists of:

• A printed circuit board on which the memory chips are located.
• A connector that required to connect the module to the motherboard.

Types of DRAM

• SDR SDRAM (single data rate synchronous DRAM) is a type of DRAM that operates in synchronization with the CPU clock frequency. It has been produced since 1993. The peculiarities of this type of memory are the implementation of a clock generator to synchronize signals and the application of pipeline information processing. Pipeline information processing is the ability to receive (read) a new instruction before the previous instruction is fully resolved (write). This kind of information processing allows more instructions to be executed at the same time. SDR SDRAM has 168 pins and two notches in the connector. Operating frequencies: It operates at 100 MHz or higher on the system bus.
• DDR SDRAM (double data rate SDRAM, or SDRAM II) - synchronous dynamic RAM with double data rate. It has been produced since 2000. It operates similarly to SDR SDRAM, only twice as fast. This type of DRAM can process two read and two write instructions per clock cycle. DDR SDRAM contains 184 pins and one slot in the connector. Operating frequencies are 100, 133, 166, and 200 MHz. The clock frequency ranges from 100 to 200 MHz, and data is transmitted at 2 bits per clock pulse. This means that the effective data transfer frequency is between 200 and 400 MHz.
• DDR2 SDRAM. It has been produced since 2004. It is faster than DDR SDRAM since it can run at higher clock frequencies. It has a large number of pins - 240. Operating frequencies: 200, 266, 333, 337, 400, 533, 575 and 600 MHz. Effective transfer frequencies can be 400, 533, 667, 675, 800, 1066, 1150, and 1200 MHz.
• DDR3 SDRAM is based on DDR2 SDRAM. It has been produced since 2007. It uses the same number of pins as DDR2 SDRAM - 240. It has improved performance due to improved signal processing, higher memory capacity, lower power consumption (1.5 volts), and higher standard clock speed up to 800 to 2400 MHz.
• DDR4 SDRAM - based on previous generations of DDR technology. It has been produced since 2014. There are 288 pins. It is distinguished by higher frequency characteristics and lower supply voltage. DDR4 bandwidth can reach 25.6 Gb/s, in case the effective frequency is increased to 3200 MHz. Secure DDR4 performance is assured by the implementation of a parity mechanism on the instruction address buses. Operating frequencies: A range of 1600 to 2400 MHz was originally set, with the possibility of increasing up to 3200 MHz.
• DDR5 SDRAM - based on the technologies of previous generations of DDR. It has been produced since 2020. The number of pins is 288. It is featured by higher frequency characteristics, maximum module volume, and lower supply voltage. The module bandwidth reaches 32 GB/s, with a maximum effective frequency of 8400 MHz.

DIMM connectors on the motherboard

DIMM is a DRAM memory connector (form factor) that has latches on both ends. These connectors have a different number of pins that are compatible with specific memory module pins.