Everything about powersupplies like wattage and rails and what wattage you need for your pc.
What is system memory and what are the differences between DDR, DDR2 and DDR3 memory. Specifications explination and the importance of system memory to system performance.
Keep your harddisk as empty and as clean as possibly. Defragmentation if needed once or twice a month. If a lot of software is uninstalled or installed defragmentation is very smart. Use NTFS as a file system for you harddisk. Disable 8.3 filename creation when no old programs that need it are...
Things to know about a harddisk. Like interfaces, specifications, technologies, and what they mean. How to recognise if a harddisk is fast or not.