As far as desktop workstations are concerned the HP Z640 is in a class of its own. Primarily a dual CPU machine, it is also perfect for architects that want a workstation to grow with their needs. Start off with a single processor then add a second later, when multi-threaded design viz workflows become more demanding.

With the second CPU housed on a riser module, along with dedicated memory and cooling fans, a CPU upgrade can literally be done in seconds. There's no messing about with thermal paste and heatsinks - levers, green touch points and blind mate connectors help mount the module effortlessly on the motherboard. It's an extremely impressive piece of engineering that also results in a notably compact 175 x 465 x 445mm chassis (as the CPU and memory sits on a board of its own, less space is taken up on the motherboard).

This theme of serviceability continues throughout the HP Z640. The side panel comes off easily with a pull on the handle, drives clip into trays that automatically connect to power and data, and should the power supply unit (PSU) develop a fault it can be disconnected, pulled out and replaced in under a minute. Everything about the chassis is designed for easy upgrades and repairs. No tools needed and no fiddly screws to lose.

The chassis itself is solid and well constructed. A handle at the front is integral to the industrial design, while another pops out at the back making it easy to lug the 15kg machine around the office. A new slimline DVD drive leaves two 5.25-inch bays free at the top of the machine for additional drives or I/O options, including a media card reader.