Andrew Cunningham on the New MacBook Pros With Touch Bar

Andrew Cunningham, writing for Ars Technica:

When you hook one of LG’s 5K monitors to one of the new MacBook Pros, what you’re actually seeing on the screen is two pictures stitched together to make a single seamless image. This is because the version of the DisplayPort spec supported by Intel’s GPUs and almost all monitors these days — version 1.2 — doesn’t have enough bandwidth to drive a 5K display at 60Hz all by itself. This will change with DisplayPort 1.3, which is right on the cusp of going mainstream, but it’s not here yet. Apple is actually pushing two DisplayPort 1.2 streams to the monitor over the single Thunderbolt 3 cable.

These kinds of workarounds were common in the early days of 4K displays before the DisplayPort 1.2 spec went mainstream, although you’d typically actually need two physical DisplayPort cables to make it happen. Apple actually uses a variation of the same idea for the 5K iMac’s internal display.

There’s nothing wrong with this method, except that it cuts down on the number of external displays your computer can support. Intel’s integrated GPUs can drive a total of three displays, but you use up two of those three streams to drive one 5K monitor and one of them to drive the laptop’s internal display. AMD’s GPUs support up to six displays, so you can use two of those connections for one 5K monitor, two of them for the other 5K monitor, one for the laptop’s internal display, and still have one left over for yet another monitor if you really wanted to use one.

This is why the 13-inch Pros can only use one 5K Thunderbolt display and the 15-inch Pros can use two of them, and it explains why Apple chose to go with AMD’s GPUs across the entire 15-inch lineup. It’s difficult enough to explain the differences between the $1,499 “MacBook Escape” and the model with the Touch Bar; imagine how much more complicated that becomes if you’re selling some 15-inch models that can drive two 5K monitors and some that can only drive one.

If you’re looking for a review with a thorough set of benchmarks — CPU, GPU, SSD, and more — this one is it. There’s quite a bit about the new MacBook Pro with function keys that’s different from its Touch Bar equipped siblings — the “MacBook Escape” feels apt.

★ Tuesday, 15 November 2016