I have 2 LG 4k monitors (bought at same time), I use the DisplayPort with a USB-C dongle, same brand (also bought same time) KIWIBIRD.
The first monitor works on 60hz, the second on 30hz.
if I unplug the first. The second changes to 60hz.
The spec clearly says I should support 2 4k 60hz monitors.
https://support.apple.com/kb/SP755?locale=en_GB
Any help?
Thanks for you patience,
Problem is fixed now, I'm leaving here the steps in hope it can help somebody else one day.
So I swapped the USB-C slots, 2nd monitor stays 30hz.
I swapped the adapters, 2nd monitor stays 30hz.
I disconnect the 1st monitor, 2nd monitor (now alone) gets 60hz.
I reconnect 1st monitor, 2nd monitor gets 30hz.
Then I go through the preferences (sure I've done it before at some point)
and find out the display for the 2nd monitor is scaled, not default.
But it is scaled to the 1st option setting, which doesn't change anything.
So I change it to default, and it get 60hz!
I change it back to scaled 1st option, looks the same, still 60hz.
I tried all the scaled options, stays 60hz.
So I end up leaving it on the default option, now 60hz.
So it all seemed to be a glitch? The 1st and last option of the scaled bar shouldn't impact performance anyway.
but even the in-between options with "degraded performance" were in 60hz.
anyway, seems that changed it to default made the tricky, all fixed now.
Thanks all for the support and patience.
Thanks for you patience,
Problem is fixed now, I'm leaving here the steps in hope it can help somebody else one day.
So I swapped the USB-C slots, 2nd monitor stays 30hz.
I swapped the adapters, 2nd monitor stays 30hz.
I disconnect the 1st monitor, 2nd monitor (now alone) gets 60hz.
I reconnect 1st monitor, 2nd monitor gets 30hz.
Then I go through the preferences (sure I've done it before at some point)
and find out the display for the 2nd monitor is scaled, not default.
But it is scaled to the 1st option setting, which doesn't change anything.
So I change it to default, and it get 60hz!
I change it back to scaled 1st option, looks the same, still 60hz.
I tried all the scaled options, stays 60hz.
So I end up leaving it on the default option, now 60hz.
So it all seemed to be a glitch? The 1st and last option of the scaled bar shouldn't impact performance anyway.
but even the in-between options with "degraded performance" were in 60hz.
anyway, seems that changed it to default made the tricky, all fixed now.
Thanks all for the support and patience.
It is possible you may be reading those specs to optimistically. This is what Everymac reports:
2nd Display Support:Dual/Mirroring* 2nd Max. Resolution:5120x2880*
Details: *In addition to simultaneous support of the internal display, this model supports a single external display up to
5120x2880 at 60Hz at over a billion color, up to two displays up to 4096x2304 at 60Hz at millions of colors, or up to two displays up to 3840x2160 at 60Hz at over a billion colors via Thunderbolt 3 (USB-C).
their specs report what is supported over ThunderBolt, which is the same as if you convert to DisplayPort family.
Use of "legacy" interfaces such as HDMI requires the ENTIRE screen be sent every 60th second, and there may not be enough bandwidth over "legacy" interfaces to support BOTH Billions of color AND 60 Hz data at nominal 4K resolution on two displays.
I am sorry for any and all mis-communication.
If you swap the adapters with each other, and change nothing else, does the problem move with the adapter?
Can you post a link to the exact adapter you are using?
Hey there adriano114,
Thanks for reaching out to Apple Support Communities. I understand you’re having issues both your 4K displays at 60Hz the same time. I’ll be happy to help with this.
Look at this link for info on how to resolve video issues on your displays:
Get help with video issues on external displays connected to your Mac
Take a look at the info under ‘Multi-stream transport (MST) displays in this link for more info on how this should work:
Use 4K displays, 5K displays, and Ultra HD TVs with your Mac
I hope that helps.
Hi,
sorry, perhaps you didn’t read my post or saw my screenshot. I’m using DisplayPort with USB-C connectors and it does work on 60hz.
the problem lies on 2 the same time :(
my spec says it does support. Is it wrong then?
The explanations in
system preferences > displays ...
... are simply awful
menu >about this Mac (System Report) > Graphics & Displays ...
... shows the actual resolution, and the Terminology used in the line below it SHOULD be used throughout MacOS, but is not.
This is from a Mac Pro silver tower:
Displays:
Display:
Resolution: 2560 x 1600
UI Looks like: 2560 x 1600
Framebuffer Depth: 24-Bit Color (ARGB8888)
"User Interface (UI) Looks like" is a terse summary of what is happening in "Scaled". Graphics are shown at the true resolution. Text (the User Interface) is doubled or scaled up in software so that it can be more legible, and "looks like" the size shown. But the actual screen resolution remains at a very high setting.
My MacBook, connectors and monitors meet all requirements for the 4K 60hz.
and it works for 1 monitors, but not 2.
:(
MacBook Pro 2018, second monitor don't support 60hz
