HP Z820 Repairability Score: 10 out of 10 (10 is easiest to repair)

The Z820 is insanely modular, even for a PC desktop, and full of user-replaceable and upgradeable parts.

A whole mess of parts can be pulled out without touching a screwdriver: power supply, hard drives, RAM, optical drives, PCI expansion cards, motherboard assembly, and several fans.

The heat sink screws are combination flathead/Torx, which pairs accessibility with quality.

Lots of room for upgrades means lots 'o' service from this machine.

HP created and shares an entire set of repair and replacement manuals with the world, empowering anyone to fix their workstations. Way to go HP!