The HP Z420 has a faster storage speed than most many processor cores PCs that were launched around the same time as it. This desktop computer has an HDD storage media, whereas most computers that are a comparable age to it have a Flash storage media. 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.
An HDD storage media is actually the worst storage speed across all computers of a comparable spec and age to the Z420.
The best storage speed amongst comparable types of desktop computer is SSD.