When someone says their computer is low on memory… what exactly do they mean? Are they running out of space to save files, or is the computer running slow? Hard Drive Space – this is generally 40 gigabytes and up – recently into the range of terabytes of storage. This is where your files are written to and read from. This storage is saved even when the computer is off. For example, you download 100 music files and save them. These get written to your Hard Drive, not system memory.