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croco_dile

macrumors regular
Original poster
Jun 3, 2016
206
191
HI,

I have a 2015 Macbook Pro 13" Retina, and a LG 27UD88 4k monitor.

I tried to connect the laptop to the monitor using 2 methods:
1. HDMI to HDMI cable, and the max I was able to get 4k @ 30hz
2. Mini Display to HDMI cable, and the max I was able to get 1080p @ 60hz

I know the laptop is capable of doing 4K @ 60hz. What am I doing wrong?
 

croco_dile

macrumors regular
Original poster
Jun 3, 2016
206
191
Try mini-displayport to display port.

Thanks. Will give that a go.

Also, given I am waiting for the new MacBook Pro which is likely to come with USB-C and Thunderbolt 3, I might just hold off until these become available.
 

Samuelsan2001

macrumors 604
Oct 24, 2013
7,729
2,153
Thanks. Will give that a go.

Also, given I am waiting for the new MacBook Pro which is likely to come with USB-C and Thunderbolt 3, I might just hold off until these become available.

It's quite possibly the cable quality is not up to spec you'll need a mini display port 1.2 to HDMI 2.0 or DP1.2
 

Ries

macrumors 68020
Apr 21, 2007
2,330
2,918
https://support.apple.com/en-us/HT206587

HDMI max is
3840x2160 at 30 Hz refresh rate
4096x2160 at 24 Hz

You need DisplayPort and:
With OS X Yosemite v10.10.3 and later, most single-stream 4K (3840x2160) displays are supported at 60Hz operation on the following Mac computers:

  • MacBook Pro (Retina, 13-inch, Early 2015)
 
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croco_dile

macrumors regular
Original poster
Jun 3, 2016
206
191
On 30 Hz, cursor movements feels sloppy/jumpy, gives the perception that performance of the Macbook Pro is lagging.

Looks like HDMI hasn't caught up with the bandwidth required to provide 60 Hz on 4K? And why does my monitor (a very recent model) still offer 2 HDMI inputs vs just 1 DP input. Should be the other way around?
 

kalex

macrumors 65816
Oct 1, 2007
1,336
56
HDMI 2.0 is capable of doing 4k resolution. hdmi port on macbook is not 2.0 so you will need to use displayport and possibly use switchresx and clock pixel patch
 

Patcell

macrumors 6502a
Aug 8, 2016
634
302
Bergen County, NJ
As long as you connect the monitor via Displayport 1.2 (supplied by Thunderbolt 2 in this case), your machine will push 3840x2160 @ 60hz. The HDMI interface on all current Macs is HDMI 1.4, which as stated previously is limited to3840x2160 @ 30hz. Minidisplayport/ Thunderbolt to HDMI adapter will not work either - the only option to connect is Displayport or Minidisplayport.
 
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croco_dile

macrumors regular
Original poster
Jun 3, 2016
206
191
HDMI 2.0 is capable of doing 4k resolution. hdmi port on macbook is not 2.0 so you will need to use displayport and possibly use switchresx and clock pixel patch

Thanks. Makes sense and just shows how backwards the Apple pro machines have become.

And I want to also say that you guys are much more knowledgeable than Apple tech support. I rang them got transferred 3 times and they had no clue.
 
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Patcell

macrumors 6502a
Aug 8, 2016
634
302
Bergen County, NJ
Thanks. Makes sense and just shows how backwards the Apple pro machines have become.

And I want to also say that you guys are much more knowledgeable than Apple tech support. I rang them got transferred 3 times and they had no clue.

Apple is way overdue for a refresh on the Pro line; however, they could not have added HDMI 2.0 in 2015 when the current 13" Pro was released - the Intel Broadwell processors do not support HDMI 2.0.
 
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megadice

macrumors newbie
Jul 27, 2010
9
0
Hello,

Trying to solve same problem as original poster (albeit 5 years later! ha!);
2015 Macbook Pro 13" Retina, and an LG 27UN850 4k monitor

My goal is to get 60Hz at a nice high res (3360x1890 or 3840x2160).

Am I better to go from my mac;
1) thunderbolt to USB-C
-or-
2) thunderbolt to mini DisplayPort

Many thanks in advance!
 

posguy99

macrumors 68020
Nov 3, 2004
2,284
1,531
Hello,

Trying to solve same problem as original poster (albeit 5 years later! ha!);
2015 Macbook Pro 13" Retina, and an LG 27UN850 4k monitor

My goal is to get 60Hz at a nice high res (3360x1890 or 3840x2160).

Am I better to go from my mac;
1) thunderbolt to USB-C
-or-
2) thunderbolt to mini DisplayPort

Many thanks in advance!
The monitor speaks DisplayPort, the laptop speaks DisplayPort. There's no reason to do anything silly between them. Use a cable similar to this one.

 
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megadice

macrumors newbie
Jul 27, 2010
9
0
The monitor speaks DisplayPort, the laptop speaks DisplayPort. There's no reason to do anything silly between them. Use a cable similar to this one.

thank-you... i guess I'm sort of confused about the relationship between mini DisplayPort and ThunderBolt 2. I know they are physically the same but I feel like I get conflicting reports about whether they are interchangeable or not.
 

posguy99

macrumors 68020
Nov 3, 2004
2,284
1,531
thank-you... i guess I'm sort of confused about the relationship between mini DisplayPort and ThunderBolt 2. I know they are physically the same but I feel like I get conflicting reports about whether they are interchangeable or not.
They are in no way interchangeable... DisplayPort is part of the Thunderbolt specification. They are hosted on the same connector.
 
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Rimmsi

macrumors regular
Jun 19, 2021
199
68
Czech Republic
Monitor mluví DisplayPort, notebook mluví DisplayPort. Není důvod mezi nimi dělat něco hloupého. Použijte kabel podobný tomuto.

Hi, so MiniDisplay port is compatibile with Thunderbolt 2 on MBP 2015?
 
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