How big is the hard disk of the desktop computer?

The desktop hard disk is generally more than 320G and 500G. In terms of size, ordinary desktop hard disks are generally 3.5-inch mechanical hard disks.

1. capacity

As the data storage of computer system, the capacity of hard disk is the most important parameter.

The capacity of the hard disk is in megabytes (MB/MiB) or gigabytes (GB/GiB), 1GB= 1000MB, 1GiB= 1024MiB. However, hard disk manufacturers usually use GB, that is, 1G= 1000MB, while Windows still uses the word "GB" to represent the unit of "GiB" (converted from 1024), so the capacity we see in BIOS or when formatting hard disks will be less than the nominal value of the factory brand.

The capacity index of hard disk also includes the storage capacity per disk of hard disk. The storage capacity per disk refers to the capacity of a single hard disk. The larger the storage capacity of each disk, the lower the unit cost and the shorter the average access time.

Generally speaking, the larger the hard disk capacity, the cheaper the price per byte, except for hard disks that exceed the mainstream capacity.

2. Speed

Rotational speed (spindle speed) is the rotational speed of the motor spindle in the hard disk, which is the maximum number of revolutions that the hard disk can complete in one minute. Rotational speed is one of the important parameters to mark the grade of hard disk and one of the key factors to determine the internal transmission rate of hard disk, which directly affects the speed of hard disk to a great extent. The faster the rotation speed of the hard disk, the faster the hard disk can find files, and the relative transmission speed of the hard disk has also been improved. Hard disk speed is expressed by revolutions per minute, and the unit is RPM, which is the abbreviation of revolutions per minute. The larger the RPM value, the faster the internal transmission rate and the shorter the access time, and the better the overall performance of the hard disk.

The spindle motor of the hard disk drives the disk to rotate at high speed, which generates buoyancy and makes the magnetic head float above the disk. To bring the data sector to be accessed under the magnetic head, the faster the rotation speed, the shorter the waiting time. So the rotational speed largely determines the speed of the hard disk.

Ordinary household hard disks usually rotate at 5400 rpm and 7200 rpm, and high-speed hard disks are also the first choice for desktop users. For notebook users, it is mainly 4200 rpm and 5400 rpm. Although some companies have released 10000rpm notebook hard disk, it is still rare in the market. Server users have the highest requirements for hard disk performance. The rotational speed of SCSI hard disks used in servers is basically 10000rpm, and even 15000rpm, which is much better than household products. Higher rotational speed can shorten the average seek time and actual reading and writing time of hard disk, but with the continuous improvement of hard disk rotational speed, it also brings negative effects such as temperature rise, motor spindle wear and working noise increase.