Clock speed, Cache size, Number of cores

How common characteristics of CPUs affect their performance: Clock speed, Cache size, Number of cores

1.1.2 CPU performance

CPU performance — Note 1 of 1

What you need to know

Three main characteristics affect CPU performance: clock speed, cache size, and number of cores. Each can improve how quickly the CPU processes instructions, but there are limits and trade-offs to consider.

What to know

Increasing clock speed too much can cause overheating, which may damage the CPU or require expensive cooling solutions.

Key terms

Clock Speed: The number of fetch-execute cycles the CPU can perform per second, measured in hertz (Hz). Higher clock speed = more instructions per second = faster performance.
Cache Size: A larger cache can store more frequently used data closer to the CPU, reducing the need to access slower RAM and improving performance.
Number of Cores: Each core is an independent processing unit. More cores allow the CPU to process multiple instructions simultaneously (in parallel).

Exam technique

Mistake:Saying 'more cores always makes it faster'. Not all programs are designed to use multiple cores, so performance may not always improve.
Tip:When asked how a characteristic improves performance, always explain the MECHANISM — e.g. 'a larger cache reduces the number of times the CPU needs to access slower RAM, so instructions are processed faster'.
Tip:You MUST be precise with terminology. 'Clock' alone is NE (not enough). 'Speed' alone is NE. 'Cores' alone is NE. Write 'clock speed', 'cache size', 'number of cores'.

Example:'Computer A has 4 cores and 1GHz. Computer B has 2 cores and 1.4GHz. Why might A be faster for a 3D simulator?' Answer: more cores can process tasks in parallel, even though clock speed is lower.

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