Can anybody explain why my MacBook Pro 13 inch 2019 model gets much hotter when I use it with an external monitor? I use it with the lid closed (clamshell mode) and it is connected with a single USB-C cable for display signal and power. The native resolution of the external screen is 4K, but I use it scaled to 1080p for ease of use. I wanted a sharp image but a normal sized user interface. I'm not touching the laptop (obviously, with the lid closed, I use a wireless keyboard and mouse) so the heat itself doesn’t really bother me. What bothers me is that the machine seems slower when used with the external screen, perhaps because it heats up more.
Got a tip for us?
Let us know
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
MacBook gets hotter when used with external monitor
- Thread starter Sami13496
- Start date
- Sort by reaction score
Even in 1080p scale mode, the 4K monitor takes more GPU power to run than the internal display. That causes it to generate more heat. That combined with lid-closed mode, and you've got yourself a recipe for thermal throttling.
Two reasons.
1. you're pushing the GPU harder now because it has to drive an external monitor, more work equals more heat.
2. You're in clamshell mode, so the heat has less chance to evacuate.
Not in my experience. I've had this problem with my 2014, 2015 MacBook Pro 15s. It is not a problem with 2k monitors; the problem is with 4k monitors with scaled resolutions. The 13 inch MacBook Pros get hotter faster than the 15s (I had a 13 inch 2015 for a few years). The easiest fix would be to get an HD monitor.
No. The Mac running hotter with an external monitor plugged in is the case for virtually all Intel Macbooks. The ASi Macs starting with M1 no longer have that problem.
OP is using "looks like 1080p" mode which is really just straight 4k with higher-res fonts/icons/etc. It's the non-integer scale modes such as "looks like 1440p" (5k internal, downsampled to 4k by the GPU) that incur the real extra GPU load.
Still, just using 4k is pushing about twice as many pixels as for the internal display.
I have used 2K and 4k monitors with my Intel MacBook Pros and the 4k monitors really got the fans spinning. I tried external fans that pushed about 150 CFM and that helped but temps were still 60-70. I did not have the heating problems with 2k monitors but I may have been running them at native resolution. That was a long time ago so I can't recall exactly.
But just using an HD monitor should solve the problem and HD monitors are really cheap these days.
...yes, that's a solution, but at the price of a major reduction in picture quality. 1920x1080 isn't a brilliant resolution by modern standards - plus Apple have dropped the sub-pixel antialiasing which used to make text a bit clearer on HD, so nostalgia isn't even what it used to be. I'd at least go for a 2560x1440 display if your Mac isn't up to 4k.
What I don't think some people get is that "looks like 1080p" on a 4k display does not mean 1920x1080 - it is still full 2840x2160 with all the extra detail, but with UI elements, fonts etc. rendered at double size to make them usable (and virtually all modern software comes with high-dpi bitmaps etc. for this).
I think with a utility like SwitchResX you can enable the "low res" version of 1080p mode that really does drop the output resolution to 1080p (even on a 4k display) but you'll take a real hit in quality.
Also, its only those Intel 13" MBPs and Minis with Intel integrated graphics that really struggle with 4k - I wouldn't replace a 4k display if you're likely to get an Apple Silicon Mac in the near future.
He's running at HD though. I have all kinds of monitors and I'm one of those few people that uses 4k 27 inches at native resolution. In general, I run all of my monitors at native resolution, including HD, WUXGA, 2K, etc. I sometimes run my MacBook Pros at native resolution when I need to. Now, a new HD monitor is probably $100 or less and it solves the problem. He could probably pick one up on Craigslist for $40. That, to me, is a very efficient solution.
I'm not saying to replace the 4k. You can keep it around.
Here's an HD monitor for $40.
Monitor Dell P2412Hb 24” Full HD 1920 x 1080 LED - computers - by...
Dell P2412Hb 24” Full HD 1920 x 1080 LED Highly Adjustable Monitor DVI VGA USB Assembled Product Dimensions (L x W x H): 26.00 x 18.00 x 12.00 Inches Working well
newhaven.craigslist.org
Here's one for $30.
One further solution would be to get a 2009 iMac 27 and use it in Target Display Mode. I've seen them for $25. Not terribly power-efficient but it's a very cheap solution in terms of capital outlays.
Possibly, but all they actually said was:
Selecting "scaled" and "1080p" gets you "looks like 1080p" which, as I said, is native 4k with double-sized UI elements. You have to jump through hoops to get actual 1920x1080 (low res) modes.
Apple's naming of screen modes is really misleading and conflates resolution, UI scale and downsampling under the general heading of "scaled" - but they're trying to simplify quite a complicated solution.
- yes, if you don't mind sacrificing display quality. Plenty of 1920x1200 and 2560x1440 displays around, that we thought were the bee's knees back in the day (no need to go as low as 1080p). My point is that "looks like"/"Scaled" 1080p on a 4k display is still 4k in terms of detail and sharpness and native 1080p will look very blurry alongside it.
It's his money and his choice.
I've used 2k iMac 27s and they are as clear and sharp as running 2k scaled on a 4k monitor. My problem is that I tend to run 4k native on 27 inch monitors.
To clarify I use “looks like 1080p” so the UI and everything would look normal size (usable for me) but it’s still native 4K so image quality is sharp and crisp. I used to use my MacBook without external screen but 13 inch screen was small and I decided to get an external monitor. First I bought HD 1920 x 1080 monitor but couldn’t use it because I was already spoiled by MacBook’s beautiful retina screen. So I returned that and got 4K monitor which has been great, almost as sharp as MacBook’s screen in terms of PPI.
MacBook’s 13.3-inch display has 2560 x 1600 native resolution. External 4K display has 3840 x 2160 native resolution. I’m wondering is that difference in resolution really enough to push the machine that much harder. Or is it also external vs internal display technology.
MacBook’s 13.3-inch display has 2560 x 1600 native resolution. External 4K display has 3840 x 2160 native resolution. I’m wondering is that difference in resolution really enough to push the machine that much harder. Or is it also external vs internal display technology.
It’s the Intel processor. Running an external display pushes its integrated GPU full tilt.
Apple Silicon Macs don’t have that problem and continue to run cool.