Any disadvantages to running a 4K external display with a new 2015 15" MacBook Pro?

Miles Davis

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Original poster
Mar 22, 2004
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What are the disadvantages—if any—to getting a 4K external display to use with a new 2015 15-inch MacBook Pro?

In particular, I'm wondering if running a 4K display would hurt the Mac's ability to do (FCPX) video and photo work. I.e., would the Mac be overworked all the time?

For reference, I'm talking about the high-end MacBook Pro with dedicated GPU, and am comparing the Dell UltraSharp P2715Q (4K) to the U2715H. I can't see either in person, so have no idea what the U2715H looks like in comparison to my U2412M. Maybe it's so much better I don't need 4K!
 

sunapple

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Jul 16, 2013
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I use the P2715Q with my 2014 MacBook Pro 15" low-end (Iris Pro). In comparison to my previous monitor (Dell U2515h I believe; 2560x1440 25") it sometimes lags a bit in OS X animations, but it's not much. Playing full screen web video can get the fans spinning and when using the MacBook screen as a second screen the lag becomes noticeably worse.

Last week I did a little video editing in Final Cut Pro X which worked perfectly and fairly smooth.

I must say this 4K 27" monitor is the best one I've ever owned. Everything is crisp and there's lots of space. I will however probably get a faster MacBook when it comes out, with the dedicated GPU (I use SolidWorks a lot). I imagine that would make a great difference with this amount of pixels to handle. Can't say my current machine is totally too slow though.
 

maflynn

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May 3, 2009
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What are the disadvantages—if any—to getting a 4K external display to use with a new 2015 15-inch MacBook Pro?
No disadvantages to my knowledge. I think its great to compliment the MBP with such a product. It will provide you with a larger display to work from.
 

strawbale

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Mar 25, 2011
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French Pyrenees
I use the P2715Q with my 2014 MacBook Pro 15" low-end (Iris Pro). In comparison to my previous monitor (Dell U2515h I believe; 2560x1440 25") it sometimes lags a bit in OS X animations, but it's not much. Playing full screen web video can get the fans spinning and when using the MacBook screen as a second screen the lag becomes noticeably worse.

Last week I did a little video editing in Final Cut Pro X which worked perfectly and fairly smooth.

I must say this 4K 27" monitor is the best one I've ever owned. Everything is crisp and there's lots of space. I will however probably get a faster MacBook when it comes out, with the dedicated GPU (I use SolidWorks a lot). I imagine that would make a great difference with this amount of pixels to handle. Can't say my current machine is totally too slow though.
At what scaled resolution do you use the P2715Q?
 

sunapple

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Jul 16, 2013
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At what scaled resolution do you use the P2715Q?
Forgot to mention. Usually at 2560x1440 which I prefer for normal use. I'm wondering now if this actually affects performance compared to running it on full 4k? Still the same amount of pixels of course, but with scaling applied...
 

strawbale

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Mar 25, 2011
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French Pyrenees
Forgot to mention. Usually at 2560x1440 which I prefer for normal use. I'm wondering now if this actually affects performance compared to running it on full 4k? Still the same amount of pixels of course, but with scaling applied...
I read in other theads that MBPs with non-dedicated GPU (like the 2015 13" models) that do manage to support 4k@60Hz external monitors, only do so satisfactorily at 100% (4k) or 200% (1920x1080). Reason being that any non full res setting is first doubled and than downsampled to 4k, so a 2560x1440 setting will first go to 5120x2880 and than back to 3830x2160, tus needing more processing power - ok with a dGPU, but less so withe a non-dGPU.
disclaimer: I don't know nor understand the technical ins and outs of this.
 
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sunapple

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Jul 16, 2013
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Thought about that doubling and scaling too, seems plausible. No real issues using my monitor like this though, so I'll keep using it this way. I'm still considering an upgraded MBP in the future, but I would do that anyway.