MacOS Sierra: CPU Fan constantly running when external monitor plugged in

Apple Support,

Another consequence of upgrading to MacOS Sierra even after the latest patches (10.12.2), battery drains twice as fast with a max of 2 to 2.5 hours compared to 5-6 hours on El Capitan. This has been tested on retina mid-2012 MBP 15" without an external monitor. In addition, I confirmed, through Activity Monitor (display all processes), CPU was at 1% usage for the most CPU intensive process while Idle. I have been running fewer applications under macOS Sierra compared to El Capitan and even that does not increase battery life.

To summarize, there are two major issues easily reproducible for this model:

1. Battery draining twice as fast under macOS Sierra with no processes pegging the CPU.
2. External Monitor forces cooling fans to run too often with or without "Automatic Graphics Switching".

I have tried all resets - SMC, PRAM, etc. hoping to resolve these issues.

I hope the next patch 10.12.3 or 10.12.4 resolve these issues. If not, can Apple reproduce these issues and acknowledge them, and provide a timeline of when they will be fixed or if they will ever be fixed.

Thank you.

The exact same thing happens to me. I've been trying to solve this since Sierra release. Called up support, searched the net, nothing suggested worked. No one is willing to help out at Apple and they don't really care about it anymore. "Thanks for reporting, if the developers consider it as urgent they might fix it in an upcoming update" is what they said.

I have a 2012 Retina Macbook which is and old device for them so they don't really bother.

I've found it so annoying that I almost prefer working without the external display. Any luck yourself?

Ditto - exact problem. I have had this issue since I upgraded to macOS Sierra in Oct 2016. I assumed macOS Sierra patches would fix this. I had to reset SMC several times because I started to get "Battery Service Warning" due to overheating. I also discharged the battery completely to recalibrate it. Apple, can you please fix this quickly? This is definitely reproducible on mid 2012 retina display MBP.

Thanks!

Same issue here.

I see, in forums and posts online, that this was also an issue in Yosemite.

External display causes WindowServer to hit the CPU hard, and computer heats up, slows down, fan goes continuously, etc. Pain in the arse, and a pity that after a few years of this issue occurring on OS X Apple have seemingly not fixed it.

I've seen three solutions mentioned, to potentially fix it:

1) Select Reduce Transparancy in the Accessability > Display options.

This didn't make any difference on my computer. That option was already ticked.

2) Disable separate Spaces for second monitor. I am about to try this, but even if it works it's a poor work-around. It will mean that if you make a window full screen on one display, the other display will go blank (apparently, yet to try it).

3) There have also been suggestions to reset SMC, but I've not seen anyone report this actually fixes the issue.

I have same issue with 10.12.5.

It still occurs.