MacBook 12" and external monitors - experiences
As I haven't found much info on using a 12" MacBook with external monitors (but have found some problems) I thought I would post my experiences here for the benefit of other searchers:
MacBook 12" with Dell u3415w (3440x1440) via USB-C Digital Multiport AV Adapter (HDMI):
VIDEO: Was experiencing random black screens on external monitor. After updating to El Capitan version 10.11.4 which included a firmware update for the Adapter, the problem became constant, with the external monitor crashing to black every few seconds non-stop. Switching from the HDMI to the MHL port on the monitor completely fixed this problem.
VIDEO: I am only able to get a 2560x1080 scaled resolution to fill the screen, which is a little blurry but fine for desktop tasks - selecting scaled 3440x1440 or "best resolution for this monitor" results in a 16:9 windowed appearance, with black bars to the right and left. I have not as yet found a solution to achieve ultrawide 21:9 at the native resolution (but would appreciate one).
VIDEO: The Macbook 12 easily drives a 3440x1440 display for desktop tasks like word processing and surfing. Full video HD YouTube is generally good, though gets a little choppy now and then.
AUDIO: Holding Option and clicking on the speaker icon in the Menu bar reveals selectable option to output audio to the device (monitor). On this monitor, there appears to be an issue receiving the signal from the Macbook when another device is plugged into another port. In my case, a PC plugged in to the DisplayPort would "shut out" the Mac audio signal but ONLY if the PC was outputting audio via external speakers, not the monitor (a lot of trial and error to discover this. When the PC sent audio ONLY to the monitor, the monitor would then accept the Mac audio signal, too. But having an external speaker hooked up via the pc mobo's 3.5mm audio cable (minijack) would somehow override BOTH the PC and Mac audio signal to the monitor. Something going on through the DP connection perhaps)
with ASUS PB27Q (2560x1440) via same Adapter, no issues.
with ASUS PA328Q plus ASUS PB287Q (3840x2160 or "4K") via same Adapter. Extremely laggy cursor/desktop until you enable DP (Displayport) 1.2 via the Monitors' onscreen settings. This enables the Macbook to drive a 4K monitor at 30Hz, which is still a little laggy, but workable enough to be productive for word processing, surfing, etc. Would not recommend a 4K monitor for the Macbook 12 for a truly "enjoyable" experience until/unless 60Hz is an option.
Hope someone finds any of this helpful.
MacBook (Retina, 12-inch, Early 2015), OS X El Capitan (10.11.4)
