CPU Performance
Learn how Clock Speed, Cores, and Cache interact to determine exactly how fast a processor can execute instructions.
Concept Explorer: The Data Pipe Bottleneck
A fast Clock Speed executes data quickly. A large Cache provides a wider "pipe" to hold more data close to the CPU. Tweak the sliders to see how they combine to affect the flow (bandwidth) of instructions.
The Three Factors
Clock Speed
Measured in Hz
Determines how many Fetch-Execute cycles the CPU can perform per second.
E.g. 3.0 GHz = 3 Billion cycles per second.
Cache Size
Measured in MB
Small, super-fast memory on the CPU that stores frequently used instructions.
A larger cache reduces the time spent waiting to fetch data from slower RAM.
Number of Cores
Single/Dual/Quad
A complete processing unit. Multiple cores allow instructions to be executed simultaneously (Parallel Processing).
Quad-core means up to 4 instructions fetched and executed at the exact same time.
Check Your Understanding
Examiner's Eye Trap
1. Why is a 2GHz Quad-Core processor NOT always four times faster than a 2GHz Single-Core processor?
2. When examiners ask "Explain how clock speed affects performance", what specific terminology must you use to gain full marks?
Written Exam Scenario (AO2/AO3)
"Company X needs to run a complex database query software. The software requires processing identical data requests independently across millions of users. Discuss whether Company X should prioritize upgrading their Clock Speed or Number of Cores to improve performance." (3 marks)
Company X should prioritize upgrading the Number of Cores.
The scenario states the software processes queries independently across users, meaning the task is highly suitable for parallel processing.
Therefore, having multiple cores means the CPU can fetch, decode, and execute multiple independent user database queries simultaneously at the exact same time, vastly improving throughput compared to a single-core processing them one by one, regardless of its clock speed.