Computer Cases
What is the main purpose of computer case ?
It holds and protects internal parts—like the motherboard, power supply, and drives—from dust, moisture, and physical damage. It also helps manage airflow to keep parts cool
What is the main purpose of a system clock?
It controls the speed and timing at which the CPU retrieves and processes instructions
Why does a processor need a cooling system?
A CPU generates massive amounts of heat while running. Without a heat sink and fan or liquid cooler, the processor will quickly overheat, leading to system crashes or permanent hardware damage in less than a minute.
What are the four core stages of a standard machine cycle?
Fetch: The CPU retrieves the next program instruction from the system's main memory (RAM).
Decode: The Control Unit (CU) translates the retrieved instruction into signals the computer can understand.
Execute: The Arithmetic Logic Unit (ALU) or other processing units carry out the commanded operation (such as a mathematical or logical calculation).
The final result of the execution is written back to memory, a system register, or sent to an output device.
What is a computer register?
A register is a tiny, high-speed storage area inside the CPU made up of flip-flops. It holds data, instructions, or memory addresses that the processor is actively using or working on right now.
What are the common sizes of PC cases?
The most common sizes are:
• Full tower: Very large, fits massive cooling setups and multiple graphics cards.
• Mid-tower: A balanced, popular size for most standard gaming and work PCs.
• Mini-tower / Small Form Factor (SFF): Compact and portable, though it limits component size.
What physical component generates the system clock's signal?
A small quartz crystal located on the motherboard
Where should you apply thermal paste during installation?
between the top of the CPU and the bottom of the heat sink. It fills microscopic gaps to maximize heat transfer efficiency.
What is the first machine cycle of any instruction always called?
Opcode Fetch. During this phase, the microprocessor reads the operation code (opcode) from memory to determine what action needs to be executed. Because every instruction must have an action, an opcode fetch is mandatory for all operations.
What does the Program Counter (PC) do?
The Program Counter stores the memory address of the next instruction that needs to be fetched and executed. After each fetch, it automatically updates to point to the next instruction in sequence.
How do you check if a component will fit in a case?
You must verify component clearances against the case specifications. Key measurements include maximum graphics card length, CPU cooler height, and liquid-cooling radiator support
How is the speed of a system clock measured?
In hertz—typically megahertz (MHz) or gigahertz (GHz)—representing millions or billions of cycles per second.
What is the correct order for installing a processor cooling assembly?
• The proper installation sequence is:
1. Install the CPU into the motherboard socket.
2. Apply the thermal paste.
3. Mount the heat sink.
4. Attach and plug in the fan.
What is the difference between an instruction cycle and a machine cycle?
An instruction cycle is the total time it takes for the CPU to fully complete one single program instruction. A machine cycle, on the other hand, is the time required to complete one basic hardware operation (like a memory read or write). Depending on how complex an instruction is, a single instruction cycle may require one or more machine cycles to finish execution
What is the Memory Address Register (MAR)?
The MAR holds the exact physical memory address of the data or instruction that the CPU needs to read from or write to in the main memory (RAM).
Why is airflow important in a computer case?
Airflow prevents parts like the processor and graphics card from overheating during heavy use. Cases with mesh panels and multiple fan mounts provide better ventilation and keep performance stable
What are small, rapid variations in a system clock signal called?
Jitter, which describes tiny timing instabilities
What is the difference between active and passive heat sinks?
An active heat sink includes an attached fan to actively blow air away from high-heat components like the CPU. A passive heat sink relies purely on metal fins and natural airflow without a fan, making it quieter and more reliable for lower-heat parts like memory modules
How does a T-state relate to a machine cycle?
T-state represents the smallest unit of time in a CPU, corresponding to exactly one internal clock pulse (or one tick of the system clock). A single machine cycle is made up of one or more T-states. For instance, in an 8085 microprocessor, an opcode fetch machine cycle typically takes 4 to 6 T-states to finish processing [1.1.2).
What is the difference between MAR and MDR?
The MAR holds the address of the memory location being accessed, while the Memory Data Register (MDR)—also known as the Memory Buffer Register—holds the actual data or instruction that was read from or is waiting to be written to that memory location.
What materials are computer cases made of?
Most cases use a combination of steel for structural strength, aluminum for lightweight builds, and tempered glass side panels to display internal components. Plastic is also used for accents and front panels.
Does the system clock keep track of the current time of day when the computer is turned off?
No, the system clock only syncs hardware operations while running; a separate Real-Time Clock (RTC) powered by a small CMOS battery tracks the calendar date and time of day when powered down
How does thermal throttling protect an overheating processor ?
Throttling is a built-in safety feature that automatically lowers the processor's clock speed and voltage when temperatures get too high, reducing power consumption and heat output to prevent damage
How do modern processors optimize the machine cycle to run faster?
Modern processors use a technique called pipelining. Pipelining acts like a factory assembly line. Instead of waiting for one instruction to finish all four stages (Fetch-Decode-Execute-Store) before starting the next, a pipelined CPU works on multiple instructions simultaneously. While one instruction is being executed, the next instruction is already being decoded, and a third is being fetched, significantly maximizing CPU efficiency
What is the Accumulator (ACC)?
The Accumulator stores the intermediate and final results of arithmetic and logical operations performed by the Arithmetic Logic Unit (ALU).