2 identical displays, different Res!

[John Fleming]

Hey All,

I really need your help. I have a Macbook pro running Catalina and just added a 2nd identical monitor to the one I already had. Both are a month apart in age, and both are a Samsung 4K U32R59X.

The problem is (apart form displaying a different colour - even though both have been factory reset) when I try and scale (4k is too small for me) they end up different resolutions. Even when I hover over over one of the scaled icons, they show different "looks like" amounts.

When I look at the arrangement window, they are different sizes. Both in 4K, they are fine and identical (apart from colour)

I have tried swapping dongles etc - no difference.

Any ideas?

Cheers
J

 

[casperes1996]

Sounds peculiar. As for the colour that could just be panel-to-panel inconsistencies. Not all panels are produced to the same colour standards that Apple’s displays are. But check the colour tab and make sure they’re set to the same colour profile.

As for the resolution, what is the middle scaled resolution on both of them? The one that’s @2x should be equivalent to 1080p screenspace wise on both

 

[iMacDragon]

Sounds like must be some kind of EDI information difference, though it does sound odd.

 

[John Fleming]

So one size on the middle scaler (there are 5 of them) is 2560 x1440 and the other is 3008 x 1692

I have also found out that both are running at a different rate.
One monitors info shows - 67.4khz 30hz at 3840 x 2160 the other is 134.8khz60hz at 3840 x 2160.

Now, depending how I plug them in, I can get either monitor to show 67 or 134. So it's not a single monitor issue

 

[iMacDragon]

and how are they being plugged in?

 

[John Fleming]

Both through Apple Dongle USB-C

 

[casperes1996]

So one size on the middle scaler (there are 5 of them) is 2560 x1440 and the other is 3008 x 1692

I have also found out that both are running at a different rate.
One monitors info shows - 67.4khz 30hz at 3840 x 2160 the other is 134.8khz60hz at 3840 x 2160.

Now, depending how I plug them in, I can get either monitor to show 67 or 134. So it's not a single monitor issue

That fact makes me think that you have cabling problems. You say it's both through the Apple USB-C dongle, but what cable attaches to that dongle? It may be a different spec. What does SI show about both monitor connections?

 

[John Fleming]

That fact makes me think that you have cabling problems. You say it's both through the Apple USB-C dongle, but what cable attaches to that dongle? It may be a different spec. What does SI show about both monitor connections?

Both are identical. The cables are the ones that came with the monitors, and the dongles are both the same apple model

 

[John Fleming]

They are these ones, and I note for my laptop (2016 Pro) it states that it should only run (3840x2160) at 30Hz

But I can get it to run at 60Hz. Very strange.

USB-C Digital AV Multiport Adapter

USB-C Digital AV Multiport Adapter lets you connect your Mac with USB-C or Thunderbolt 3 (USB-C) ports to HDMI displays, standard USB devices and charging cables. Buy now at apple.com.

www.apple.com

 

[John Fleming]

So I have ordered one of these... should fix the issue.

CalDigit Thunderbolt 3 Mini Dock

The CalDigit Thunderbolt 3 Mini Dock is a bus-powered dock that lets you connect your Thunderbolt 3-equipped Mac to two HDMI-enabled TVs or displays. Buy online now at apple.com.

www.apple.com

 

[raknor]

Both are identical. The cables are the ones that came with the monitors, and the dongles are both the same apple model

Are you attaching these via HDMI cables? Did you purchase both Apple USB-C dongles at the same time?

there are two versions of the Apple USB-c Multiport AV adapter. The older one only supports HDMI 4K at 30Hz, the newer one supports 4K@60HZ (HDMI 2.0).

i suspect you have two different models. Apple doesn’t distinguish them in any way obvious way on the adapter but they have different model numbers.

About the Apple USB-C Digital AV Multiport Adapter - Apple Support

Connect a Mac that has a Thunderbolt 4, Thunderbolt 3, or USB-C port to an HDMI display, while also charging your Mac and connecting to a USB-A device. iPad models that have a Thunderbolt or USB-C port can also use this adapter.

support.apple.com

The dock you bought will fix it since it has 2 HDMI 2.0 ports. You could order 2 Display Port to usb-c cables since your display supports it or just buy a newer Apple usb-c dongle. Both those options would be cheaper than the dock.

 

[John Fleming]

Thanks man. The dock will come in handy as I am forever plugging in USB drives etc, and will be a neater solution. So all good! I would suggest I have the older dongle.