The HP Z640 has a faster storage speed than most personal computers of a comparable type and age to it. This personal computer has an HDD storage medium, whereas most comparable spec personal computers that have been available for around the same time as it have a Flash 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.
There are a number of alternative HDD desktop computers currently available which you might also want to look at including cheaper computers such as the HP Z840, or the Lenovo P900.
If the storage speed of this HP computer is not fast enough for you then you might also want to consider the Thinkstation P500 (SSD), or the P900 (SSD) both from Lenovo or the HP Z640 (SSD).