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XNorth

macrumors 6502
Original poster
Feb 23, 2018
286
337
United States
Here’s a trick to use clamshell mode and save power without sacrificing air flow through or across the keyboard. I call this open clamshell mode.

The lid/main display will turn off without closing all the way. Slowly close the display to about an inch of the palm rest, about the width of a thumb. I use my thumb as a stop to quickly block the lid from closing. the display will turn off, and the extrnal display switches on as the main display. The gap allows better airflows than completely closed. This also works on a vertical stand with the lid open facing up.

Honestly, I don’t know if there is any difference in temps between clamshell mode and open clamshell mode, but I have been using my MBP 16" in open clamshell mode only when I’m not mobile. If anyone is willing to compare the temps and show open clamshell has lower temps, then this would be a legit way to have your cake and eat it too.

open-clamshell.jpg
 
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profcutter

macrumors 6502a
Mar 28, 2019
560
246
You can also just very carefully place a small magnet on the hall effect sensor on the top case. That will fool the computer into thinking it's closed, and you can have the display all the way open. On my old 2013 MBP, it was just about an inch from the hinge on the left speaker.
 
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profcutter

macrumors 6502a
Mar 28, 2019
560
246
The Hall effect sensor may be at a different spot on the 16. Maybe take a paper clip and run it around the edge of the screen, not touching but very close. If it pulls in a certain place, that’s probably where the sensor is. Just a thought. I found mine on some schematic I found a few years ago.
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The magnet puts the computer to sleep, but if you give it any input while the magnet is present, the internal screen remains off and the computer wakes up.
 
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XNorth

macrumors 6502
Original poster
Feb 23, 2018
286
337
United States
Air is not channeled through the keyboard, but external airflow over the keyboard likely helps with heat dissipation when the keyboard and the Touch Bar get hot.
 
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XNorth

macrumors 6502
Original poster
Feb 23, 2018
286
337
United States
The magnet puts the computer to sleep, but if you give it any input while the magnet is present, the internal screen remains off and the computer wakes up.

I can confirm that magnets don't work on my MBP 16". Maybe I'm not doing it right. The upper corners of the lid and edges of the palm rests are magnetized, but attaching a magnet to any of these spots have no effect.

Regardless, I prefer the open clamshell mode. I like the space saving low profile tucked under the monitor, in addition to the other benefits.
 
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profcutter

macrumors 6502a
Mar 28, 2019
560
246
The trick is to put the magnet on the topcase in the area corresponding to where the magnets are on the lid. The lid holds the magnets, the topcase houses the sensors. The sensors detect when the magnets come near.

One summer, when I was writing a book, I had the laptop raised up so there was some airflow underneath, it was connected to a 4K monitor, with the magnet on the topcase and the lid open, I could run the monitor at 60hz, and the fans ran like crazy. I never bothered to check if it ran cooler that way, but you could feel the hot air escaping above the keyboard, I figured that wasn’t good for the display to absorb when it was closed.
 
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