Conclusion: The Z420 is priced fairly for the level of validation and support HP pours into its offering, and this is really where the system makes sense: moderate-demand visual computing for a low- to moderate-range budget. If you're really serious about graphics performance, look higher up HP's stack to the Z620 or Z820. But if you're seeking dependability and support backed by decent speed, then the Z420 is a great fit.
Pros: Potent performance, SSD plus hard drive storage, Plenty of expansion slots
Cons: No Thunderbolt or eSATA ports, Consumer- rather than industrial-grade hard drive
Conclusion: HP has done a great job of filling this workstation with great components, but still keeping the price low. If you are looking for workstation for your office then I recommend you look at the HP Z line of workstations. With such a variety to choose from it will be easy to find one that fits perfectly with your needs.
Conclusion: There aren't many reading this that need massive amounts of power for specific and often crucial tasks. But for those who do, and can afford the premium that a workstation demands, the Z420 is an excellent choice. While not as flashy as the machines above it or as compact as those below it in HP's line, it strikes a happy medium while keeping a wide variety of initial configuration and upgrade options.