The CPU (Central Processing Unit) or processor, is arguably the most important component in a computer. It’s responsible for processing instructions and controlling the other components. Many CPUs include basic on-board graphics too so you can power a display without needing a separate graphics card. AMD’s new performance Ryzen processors offer a wide range of models suited to different tasks and budgets. Low-end, dual-core chips can be had for £25 or even less, but are only well-matched to basic tasks, while high-end Ryzen CPUs are multi-core, high-frequency monsters that can tear through the world’s most intensive software. Before buying, ensure you’ve got a compatible motherboard and a cooler that can take the heat.