[threedots]

The 16" MBP is terrible with an external monitor (or at least mine is with my external monitor). Fans spin up like crazy and the case gets hot enough to fry an egg on. It's the one terrible weakness of an otherwise great machine.

[eyelidlessness]

I’ve had this experience and seen many others mention it too. I always make a point when I have time to mention how I’ve solved it.

If you haven’t already, try plugging the power in on the right side, and the display/any other peripherals on the left. It sounds crazy, but this has been the solution for tons of people. Apparently the heat generated by power input (even at a steady full charge) is enough to spike the sensors near the components on the left side.

I haven’t experienced any downsides to this change other than having to spend a few minutes rearranging stuff on my desk.

[dtech]

That seems crazy but plausible. Explains why so many people complain about it while my office and home never had issues, it's all laid out so you plug in the power on the right.

[eyelidlessness]

It apparently affects all of the USB-C models with ports on both sides, it’s kind of surprising to me that the workaround isn’t more well-known, and even more surprising that it’s gone so many generations without a fix (although honestly I have no idea how involved the fix would be, and it’s probably moot with Mx around the corner).

[joegahona]

Just confirming: By "right side," you mean _my_ right when looking at the computer? "Left side" is the side closer to the Esc key?

[eyelidlessness]

Yes, I should have clarified that.

[mh-]

What side should one use if they're using a thunderbolt 3 display? (power and video in the same usb-c cable then)

[eyelidlessness]

I’d try:

1. Plug it all in right side and see how it goes. The important part is that power needs to be on the right, the point of plugging other stuff on the left is just to distribute heat/load.

2. If that doesn’t help/causes other issues, are you willing to separate power delivery and plug in two cables? I know it’s annoying when the spec supports single-cable everything, but in the scheme of things it’s not a terrible trade off to have a more usable machine.

[jsjohnst]

I wish we could narrow down why some have this experience and others don’t. I’ve connected 8 external monitors (all at once) to three different 16” MBP and still couldn’t produce a similar issue as some have with just one.

[thatswrong0]

Yeah this this has been abysmal for me. It does this even if you use it with the main display closed (clamshell mode)

Makes my 2018 "Pro" machine feel like an 8 year old device struggling to keep up with very basic tasks because of thermal throttling (and this is even after getting the fans cleaned by Apple recently)

[eyelidlessness]

Clamshell mode is generally worse for thermals. Even though you’re not dedicating power to the internal screen, you’re trapping more heat in the case. Other than that, take a look at my sibling comment for a potential solution.

[Qub3d]

Yeah, its a known limit of the Intel CPU. I'm no expert, but my understanding is that any external monitor essentially requires pushing through the dGPU and therefore your system will be consuming ~100W minimum, no matter the load.

[x3sphere]

Had the same issue. I sold my 16" MBP and moved to the 13" M1 MBP. Performance is comparable (if not slightly better) and the fans almost never go on unless I'm compiling code and maxing out all cores.

[emrah]

I have an external monitor with my 16" MBP and it works great. I haven't experienced any of the issues you mention. I have one of the Apple monitors though. It might be an issue with non-Apple monitors.

[nklmilojevic]

How is that? Which external screen do you run?

Mine is 3840x1600 (38") and MBP 15.4 (with discrete AMD graphics) and fans never spin up just because it is hooked on external screen.

[breck]

Oh wild, didn't know that. This is the M1 16" MBP, or the older Intel one?

[eyelidlessness]

Only the low end 13” MBP has an M1 release currently.

[justincormack]

The old one, there isn't an M1 16" yet

[breck]

Ah thanks! Didn't realize that.

[varjag]

There's no M1 16" MBP.