Choosing an... Internal hard disk
A basic 1TB internal hard disk should cost around £40. This will be fast enough for general use and will provide enough storage for most users.
Make sure the hard disk you choose has the appropriate interface type for your PC. Some mechanical hard disks still come with SATA2 interfaces, but newer models and most solid-state drives (SSDs) have faster SATA3 interfaces. You’ll need a motherboard with a SATA3 port if you want to benefit from SATA3’s faster speeds; SATA3 disks will work with SATA2 ports but can only transfer files at SATA2 speeds.
SSDs can make the most of SATA3’s extra bandwidth for fast file transfers. They use flash memory similar to that found in USB flash drives, and although they tend to provide less capacity than mechanical hard disks, they’re significantly faster.
Buy a hard disk that provides more capacity than you think you need, as your storage requirements are likely to grow. A 3TB disk strikes the best balance between capacity and low cost per gigabyte, but in general you should aim to buy the largest disk you can afford.
If you want more disk space or you want to protect your data against disk failure, think about buying several hard disks to create a RAID array. These use multiple hard disks to create one large logical disk with better performance, or to duplicate your data for better protection. RAID arrays require hard disks of the same size. In theory, they can be from different manufacturers, but it’s better to buy identical disks if you can.
A hard disk’s spindle speed determines how quickly it can transfer data. A spindle speed of 7,200rpm is common in desktop drives and is fast enough for most purposes. Desktop hard disks with 5,400rpm spindle speeds are quite slow but use less power and generate less heat and noise.
To strike the best balance between speed and storage capacity, use an SSD as your system disk and store your files on a larger mechanical disk.