In 2011, hard disk prices roughly doubled after factories in Thailand were devastated by flooding. But prices are slowly returning to their previous levels, and hard disks are affordable again. See all hard drive reviews.

A year ago, some vendors were selling 2TB hard disks for close to £150, but now you can find them for £75, if you shop around. 3TB hard disks are now better value for money as well, and even 4TB disks are now available, but are expensive at around £275 each.

Adding an extra hard disk in your PC not only increases the amount of storage space, but it can also speed it up.

When you have multiple drives installed, it’s important to check that the Bios knows which drive from which to boot. Press Delete, F2 or look for a message on-screen which tells you which key to press to enter the Bios.

Connecting a hard disk to a SATA 3 port, or buying a hard disk that supports SATA 3 makes no improvement to its performance. Hard disks are limited by their mechanical nature and, unlike an SSD, they simply can't outstrip the 3Gbps maximum transfer capacity of a SATA 2 port.

How to install a hard drive

1. With the sides of your PC case removed, insert the new hard disk into a 3.5in removable bay and secure it with screws. Connect a SATA cable in the same way as an SSD, with the L-shaped end (if there is one) connected to the hard disk, and the other end connected to the motherboard.

Older cases that lack removable bays still have space for an extra hard disk, with holes built directly into the chassis that line up with the hard disk.

Connect cables

2. When you turn the computer on, it might display an error message saying ‘NTLDR is missing’ or 'Operating system not present'. If you see that error, don’t worry. The computer is trying to load Windows from the new hard disk rather than the SSD.

This can be sorted out by entering the Bios when the computer boots up and looking at the boot order which should be in an Advanced or Boot menu, depending on your motherboard. The SSD should be given the highest priority in the boot order.

Boot order

3. When you first turn on the computer, your new hard disk may not be ready for use immediately. Open Computer Management by clicking the Start icon, right clicking Computer, then clicking on Manage. In the window that appears, click Disk Management under the Storage header, to list the disks in your computer.

Your new hard disk should be listed in the centre pane. Right click the black unallocated area next to it, then choose Create partition. It doesn’t matter whether you create a primary, extended or logical partition. Then format the partition.

Format disk

4. Your computer is likely to be configured so the c: drive is the SSD, the d: drive is the DVD writer, and the e: drive is your new hard disk (possibly f: if you installed an SSD and kept your PC's original hard disk as well).

Change drive letter

We prefer having the DVD drive as the last drive letter. To do this, in Computer Management, right-click on your hard disk’s newly created partition and choose Change Drive Letter and Paths. Click Change, then choose a temporary drive letter.

Then right-click on your DVD writer, once again choose Change Drive letter and paths, and assign it the drive letter E (or F). Finally, right-click on your new hard disk’s partition and assign it the letter D (or E).