Enlarge (credit: Peter Bright)

Most of the PC OEMs have refreshed their Skylake systems to include Intel’s new Kaby Lake chips. Kaby Lake parts are for the most part drop-in replacements for Skylake parts—same chipsets, same power envelopes and cooling requirements—and some manufacturers have taken advantage of this fact. Dell’s new XPS 13 is in most regards identical to the old XPS 13, for example, except for the processor swap. Some manufacturers have been a little more ambitious; HP’s updated Spectre x360 adds Thunderbolt 3 and Windows Hello support as well as slashing the size and weight.

Microsoft, however, has gone for none of these routes. The Surface Pro 4 with its Skylake processor remains the current iteration of the company’s productivity-oriented tablet and hasn’t changed since its introduction. The Surface Book, the laptop that can do double duty as a tablet, also remains a Skylake system. But Microsoft has made an upgrade of sorts to the Surface Book range in the form of an even more expensive version that sits at the very top of the range: the Surface Book with Performance Base.

The Surface Book’s big party trick is that the screen portion is the part that contains the computer; it has batteries, a processor, RAM, storage, and everything else. The keyboard base, the part that in a regular laptop houses the computer parts, contains only the keyboard, touchpad, and battery. On higher-end models the keyboard base also contains a discrete Nvidia GPU. This GPU is non-standard; it doesn’t neatly line up with any of Nvidia’s usual mobile parts, and while it’s faster than the Intel integrated graphics, it’s not as quick as the more mainstream numbered parts.