I have a MacBook Pro 2018 13” with the upgraded i7 processor. It is connected to a LG ultra 5K display. Before this beauty I used an old Thunderbolt Apple display with a dongle. The technical specs from Apple define that this MacBook can only run one 5K external monitor or two 4K (a 15" can manage two 5K monitors). I challenged this by connecting both displays to the MacBook and found that they work perfectly. I also have the Black Magic eGPU, the one sold by Apple connected to the 5K LG display.
It would be great to work with both monitors, seems like a dream! However since I plugged both and during 15 minutes, the fan did not stop working. The machine heated a lot and I decided to unplug it. I am worried that if I use it like this daily, it may be pushing the hardware too hard and damage the MacBook.
What do you think? Can I assume that if the display works, it means Apple prepared the MacBook to be used like this? Is the external GPU perhaps helping? Should I use the two screens on a daily basis?
Yes, it can handle that. The hardware can handle it.
Yes, otherwise you couldn’t run the second monitor.
I have a Mac mini that has the same specs for video output (1x5k or 2x4k) and I have a 5k running on the BMD eGPU and a 4k on the Mac mini. Everything works great and I haven’t seen the Mac mini stressing itself too much.
What kind of CPU temps are you seeing? GPU? I’m cautious of running at 90 all the time. That’s getting up there. But running the 60s or 70s is fine IMO.
I have found that the word “works” has to be take with a grain of salt. Get an app like iStats Menu that that can show the power metrics, fans speeds, and temperatures of different components. My 2019 Macbook 16" can handle 1 external monitor and maintain a reasonable temperature. It will overheat after 15 minutes if I connect 2 external monitors .
It’s odd because a much less powerful 2017 Macbook Pro can handle 2 external displays ok, The GPU only draws 10W like this, while the 2019 Macbook Pro’s GPU draws 20W and the temperature goes up until it crashes.
You have to do some testing and see what your device can handle while not overheating. I’m not an expert, but what I have seen from 5-6 hours of testing different external monitor setups, along with reading lots and lots of posts on reddit and forums about heat problems with external monitors, it seems like with 1 monitor temp ~58C , 2 monitors ~65C is normal. With no external displays my Macbook Pro is around ~41C .