Max external resolutions, 2013–2015 MBP15

[fhturner]

Hey Everyone—

Bit of an academic inquiry here (although w/ practical application in some rare cases)... I have a Late 2013 MacBook Pro 15" 2.3GHz w/ GT 750M GPU that's my primary machine. I also have a 2.2GHz Mid 2015 MBP 15" w/ no dGPU that I repaired/rebuilt as a secondary. In comparing the 2 machines, I realized that, since there were extremely few changes from Late 2013 thru Mid 2015, the 2013 is actually the better machine. They have the same-gen Haswell/Crystalwell CPU w/ Iris Pro 5200, and the 2013 is 100MHz faster. Plus, it has the add'l GT 750M.

The oddity I found is that Apple, in its tech specs for these machines here:

Late 2013: https://support.apple.com/kb/SP690?locale=en_US
Mid 2014: https://support.apple.com/kb/sp704?locale=en_US
Mid 2015: https://support.apple.com/kb/SP719?locale=en_US

has the 2015 model (including IG only) able to support two external 3840x2160 (4K) displays, while the nearly identical 2013 & 2014 models only support two 2560x1440 displays.

Technically....WHY would this be?? Just curious if anyone knew if this was an _actual_ limitation, or simply what Apple "jotted down" as the max supported resolutions for these machines when they were released (and thus, not a hard and fast rule). If there is an actual limitation, what hardware difference could that be attributable to?

Thx,
Fred

 

[Chancha]

In theory, All TB2 computers should handle 4k natively, since DisplayPort 1.2 is mandated. Even the weaker Iris 5200 can do 4k30Hz over HDMI, so it quite obviously is not a GPU power limit here.

It may have been the case of Apple not bothering to update the specs docs of older models, despite drivers etc are already updated to take advantage of the higher cap on the later model which uses same gen parts anyway. Or maybe at the time of 2013 release, the best TB display that Apple offered was only at 2K? Since you got both machine at hand, do you have the monitors to test yourself? I am positive that even if macOS by default doesn't let you output 4k over TB2/mDP on the 2013, installing something like SwitchRes will do it.

 

[robvas]

Here's an updated document regarding 4k/5k displays from Apple

https://support.apple.com/en-us/HT206587

 

[Freyqq]

Here's an updated document regarding 4k/5k displays from Apple

https://support.apple.com/en-us/HT206587

Even that document is out of date.

Source: I have a late 2013 rMBP with 750M and i'm running SST 4k over displayport.

 

[fhturner]

In theory, All TB2 computers should handle 4k natively, since DisplayPort 1.2 is mandated. Even the weaker Iris 5200 can do 4k30Hz over HDMI, so it quite obviously is not a GPU power limit here.

It may have been the case of Apple not bothering to update the specs docs of older models, despite drivers etc are already updated to take advantage of the higher cap on the later model which uses same gen parts anyway. Or maybe at the time of 2013 release, the best TB display that Apple offered was only at 2K? Since you got both machine at hand, do you have the monitors to test yourself? I am positive that even if macOS by default doesn't let you output 4k over TB2/mDP on the 2013, installing something like SwitchRes will do it.

Yeah, I think you are right about it possibly being specs simply not getting updated. I don't actually have any 4K displays to try it out with. I was mainly curious about the "edge" condition of running a pair of 4K displays, but I imagine the fan noise would become a nuisance doing this, at least if you are also driving the built-in display concurrently. I was running a 27" iMac (Target Display Mode, 2560x1440) and older Cinema Display 23" (1920x1200) plus the built-in last night, and just the mere act of driving them at idle w/ very little CPU or graphics demand caused the fans to come up to around 4000rpm. Playing back video and moving regularly through the interface caused them to max out around 6000rpm for extended periods.

Here's an updated document regarding 4k/5k displays from Apple

https://support.apple.com/en-us/HT206587

Yes, I had reviewed that document on several occasions, and I agree w/ Freyqq below that it is outdated and/or not completely accurate. For example, check out the bit under SST @ 4K/60Hz where it specifies MacBook Pro 15" Mid 2014 or later..... There is ZERO difference between the Late 2013 and Mid 2014 machines other than 200MHz at each clock speed tier. So that doesn't make ANY sense (there shouldn't be a differentiation between Late 2013/Mid 2014).

Even that document is out of date.

Source: I have a late 2013 rMBP with 750M and i'm running SST 4k over displayport.

Ah, ok, cool. Are you getting 60Hz? As I said above, if the Mid 2014 is specified as supporting 4K/60Hz, our Late 2013s should as well. Have you tried running a pair of 4Ks before? If not and you happen to have an extra one, don your earplugs and give it a try!

Thanks for the discussion, y'all,
Fred

 

[robvas]

Even that document is out of date.

Source: I have a late 2013 rMBP with 750M and i'm running SST 4k over displayport.

Published Date: Feb 27, 2018

 

[fhturner]

Published Date: Feb 27, 2018

I think what we meant was that the information in it was outdated, regardless of when someone hit Command-S on the file...

 

[robvas]

Ah, ok, cool. Are you getting 60Hz? As I said above, if the Mid 2014 is specified as supporting 4K/60Hz, our Late 2013s should as well. Have you tried running a pair of 4Ks before? If not and you happen to have an extra one, don your earplugs and give it a try!
Fred

That should work, I'm almost positive I have tried it before

 

[Freyqq]

Yeah, I think you are right about it possibly being specs simply not getting updated. I don't actually have any 4K displays to try it out with. I was mainly curious about the "edge" condition of running a pair of 4K displays, but I imagine the fan noise would become a nuisance doing this, at least if you are also driving the built-in display concurrently. I was running a 27" iMac (Target Display Mode, 2560x1440) and older Cinema Display 23" (1920x1200) plus the built-in last night, and just the mere act of driving them at idle w/ very little CPU or graphics demand caused the fans to come up to around 4000rpm. Playing back video and moving regularly through the interface caused them to max out around 6000rpm for extended periods.



Yes, I had reviewed that document on several occasions, and I agree w/ Freyqq below that it is outdated and/or not completely accurate. For example, check out the bit under SST @ 4K/60Hz where it specifies MacBook Pro 15" Mid 2014 or later..... There is ZERO difference between the Late 2013 and Mid 2014 machines other than 200MHz at each clock speed tier. So that doesn't make ANY sense (there shouldn't be a differentiation between Late 2013/Mid 2014).



Ah, ok, cool. Are you getting 60Hz? As I said above, if the Mid 2014 is specified as supporting 4K/60Hz, our Late 2013s should as well. Have you tried running a pair of 4Ks before? If not and you happen to have an extra one, don your earplugs and give it a try!

Thanks for the discussion, y'all,
Fred

Yeah i get 60hz. Only have the one 4k monitor, but would be curious if i could run 2.

 

[Shamgar]

As a general rule, Apple doesn’t update their official specifications for older machines to match technological developments. For instance, maximum RAM values for upgradeable machines are usually listed based on modules available at launch and not based on actual system limitations. I was also pleased to discover that the 2012 rMBP supported 4k30 just fine in practice.

 

[Chancha]

Yeah i get 60hz. Only have the one 4k monitor, but would be curious if i could run 2.

2x 4K even at 30Hz, on top of running the built-in retina screen of 2012-2015 MBPs will surely fire up too much heat. I tried it once with my maxed out 2015 15" and while it is possible being just idle, you don't get enough TDP leftover for doing real tasks.

I always thought these kind of edge case connecting scenarios are more academic than practical.

 

[Freyqq]

2x 4K even at 30Hz, on top of running the built-in retina screen of 2012-2015 MBPs will surely fire up too much heat. I tried it once with my maxed out 2015 15" and while it is possible being just idle, you don't get enough TDP leftover for doing real tasks.

I always thought these kind of edge case connecting scenarios are more academic than practical.

2 x 4K @ 30hz is the same bandwidth as 1 4k @ 60 hz. Honestly, it's not a big drain to drive that many pixels from a technical standpoint. The 750M has 2 GB of vram and can easily handle it for just web browsing, etc. Obviously running a game at 4k resolution is too much though.