If I connect a 4K monitor with a latest MBP, will there be a spike in CPU / GPU usage than normal ?
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What is the typical CPU usage with external monitors?
- Thread starter Sovon Halder
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That depends if you plan to use both the laptop screen and external at the same time. My system runs considerably hotter in that setup. Additionally since the 4K display is higher resolution than the Retina display, it will use more resources. I've noticed, even if I use the MBP in clamshell model with 4K external it still runs hotter than using the native screen. That being said, I didn't notice and slow down or lag on either screen. So yes there IS higher usage than normal, but nothing that you'll notice except if you really push the system.
Thank you for replying in this thread.
Can you put a number to this please (if you have 4K monitor)? A % of cpu usage on idle being connected to the monitor. The reason why I'm asking is that, where I live, I haven't seen anyone actually using a 4K monitor. And Im planning to purchase one. So before that, I want to know just this one thing.
iStat Menus reports that, my normal usage (web / movie / light productivity work) works the CPU around 10 - 30%. For office work i.e. Photoshop / Illustrator it's a bit higher than that (40-55-60). Now I want to have a rough idea as to what % the CPU would run at when I've just plugged in to the 4K 27UK850 and not doing anything.
Thanks again.
So this will vary greatly depending on the model MacBook you have, and the CPU that you have installed with it.
In my setup, I use 2 1080p Samsung 32" monitors, plus the internal monitor of my 2017 13" MacBook Pro w/TB 3.1ghz CPU, and with all the monitors going, and with only safari and messages running it only goes up about 5-10% above my normal usage.
Now add 4k and running a CPU hungry app like Photoshop, will add to the CPU stress, but I don't think it'd add more than 10-15% CPU pressure, which your computer can handle safely and easily. These machines are designed to handle at least one 4k monitor with ease.
Also, if you have a 15" model, you should be able to add that 4k monitor with almost no noticeable difference in performance since you have the dedicated GPU.
Thank you for posting.
I have a 2017 13" entry Touch Bar model. I believe I'm going to be okay.
EDIT: BTW, can you share a photo of your desk setup, if you don't mind. I'd love to see how you manage 2 ginormous 32" monitors.
I use a Dell P2715Q with my 2013 15-MBP. For me, it's really hard to come up with a number, because I connect this monitor so I can do more things. It's very helpful in FCPX and PS CS6. FCPX is often working in background. And, I am "one of those people" who can have multiple tabs open at once, increasing the odds that one of them will start sucking cycles like there's no tomorrow. As I type this, forums.macrumors.com in a Safari tab is using approx 9% CPU, according to Activity Monitor. Of course, using a large external display can require extra resources due to the way Mac OSX creates certain resolutions that you may choose - I often run this display at 1440p. It's usually not an issue with my personal MBP - it has a GT750M. My work MBP is the same model without a GPU and it showed signs of sluggishness.
I ran a quick test. You can see 2 small, and then 1 big spike in the CPU graphs. It did eventually settle back down towards 0% after another 10 seconds
![nwIEDyn.png]()
The first small spike is plugging in my Acer 1080p 21" monitor using HDMI/DVI
The next spike is my Acer 2560x1440 using HDMI
The last big spike is my LG 4K USB-C monitor. It looks like the CPU is doing some stuff for a bit after you connect.
The first small spike is plugging in my Acer 1080p 21" monitor using HDMI/DVI
The next spike is my Acer 2560x1440 using HDMI
The last big spike is my LG 4K USB-C monitor. It looks like the CPU is doing some stuff for a bit after you connect.
Great thread,
Great info, does this also involve the GPU?
I ran a quick test. You can see 2 small, and then 1 big spike in the CPU graphs. It did eventually settle back down towards 0% after another 10 seconds
![nwIEDyn.png]()
The first small spike is plugging in my Acer 1080p 21" monitor using HDMI/DVI
The next spike is my Acer 2560x1440 using HDMI
The last big spike is my LG 4K USB-C monitor. It looks like the CPU is doing some stuff for a bit after you connect.
Great info, does this also involve the GPU?
Here you go, not perfect wire management, and the stand I bought is a bit wonky, but it does the job...Thank you for posting.
I have a 2017 13" entry Touch Bar model. I believe I'm going to be okay.
EDIT: BTW, can you share a photo of your desk setup, if you don't mind. I'd love to see how you manage 2 ginormous 32" monitors.
And for what it's worth, here is a screenshot of the iStat CPU usage, with no apps running. Doesn't make a discernible difference on CPU usage. Like robvas showed, there is a spike when you first plug in the monitors, but after that the CPU returns to about the same level as it was with no external monitors hooked up.
Thanks for sharing the photos and the iStat info, man.
I got the info of what I was looking.