The HP Z820 has a faster storage speed than most personal computers of this type and age. This computer has an HDD storage medium, whereas most desktop computers of this age and spec have an SSD storage medium. A Hard Disk Drive (HDD) is the traditional storage method for computers. A HDD stores the information on magnetic disks. HDD drives are cheap, but they are slower than Flash and SSD bases storage systems.
If the storage speed of this many processor core desktop computer is too slow for you then you might want to look at the Lenovo Thinkstation P500 (£1,611.72) (SSD), or the HP Z440 MT (£1,323.05) (SSD).