I have the 15" 2017 MacBook Pro (with the four USB-C/TB3 connectors).
I recently bought this TV, which is my first and only 4K display: https://www.amazon.com/TCL-43S405-43-Inch-Ultra-Smart/dp/B01N29XPO3/
I purchased both of these cables:
https://www.amazon.com/gp/product/B075V5JK36/
https://www.amazon.com/gp/product/B073H9RG9T/
No matter what I do, OS X will not recognize it as 4K @ 60Hz.
The monitor says all three HDMI ports support 4K60Hz. Both cables say they support 4K60Hz. The laptop says it can support four 4K60Hz displays. And yet there's no 60Hz.
My 4K AppleTV correctly plays 4K 60Hz via HDMI to this TV.
Much googling has been done on this subject, with only two things which keep coming up:
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There's a thread where somebody finally gives up on HDMI and connects his display via DisplayPort (which I wish this had, but it doesn't)
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There's a thread where people say option-click "Scaled" in the Display preferences and can select the refresh rate. When I do so, there doesn't exist a pull-down for refresh rate.
Here's the display preferences:
Here's the system profiler information:
Radeon Pro 560:
Chipset Model: Radeon Pro 560
Type: GPU
Bus: PCIe
PCIe Lane Width: x8
VRAM (Total): 4 GB
Vendor: AMD (0x1002)
Device ID: 0x67ef
Revision ID: 0x00c0
ROM Revision: 113-C980AJ-927
VBIOS Version: 113-C9801AU-A02
EFI Driver Version: 01.00.927
Automatic Graphics Switching: Supported
gMux Version: 4.0.29 [3.2.8]
Metal: Supported, feature set macOS GPUFamily1 v3
Displays:
Color LCD:
Display Type: Built-In Retina LCD
Resolution: 2880 x 1800 Retina
Framebuffer Depth: 30-Bit Color (ARGB2101010)
Main Display: Yes
Mirror: Off
Online: Yes
Rotation: Supported
Automatically Adjust Brightness: No
43S405:
Resolution: 3840 x 2160 @ 30 Hz
Framebuffer Depth: 30-Bit Color (ARGB2101010)
Mirror: Off
Online: Yes
Rotation: Supported
Automatically Adjust Brightness: No
Connection Type: DVI or HDMI
Adapter Firmware Version: 7.55
Television: Yes
Cinema HD:
Display Type: LCD
Resolution: 2560 x 1600
Framebuffer Depth: 30-Bit Color (ARGB2101010)
Display Serial Number: CY8430JLXMP
Mirror: Off
Online: Yes
Rotation: Supported
Adapter Type: Apple Mini DisplayPort To Dual-Link DVI Adapter
Automatically Adjust Brightness: No
Adapter Firmware Version: 1.03
How do I get this to display 4K @ 60Hz?
Update: If I disconnect the 30" Cinema Display (via the dual-link-DVI adapter), I get 4K @ 60Hz. It doesn't matter if I connect it via DisplayPort to a dock or into a TB2 port on an external device, it still prevents 4K@60Hz. This doesn't make sense, especially since Apple's site says this can handle the built-in display plus four 3840×2160 @ 60Hz displays simultaneously.
Update 2: I just went back to the system preferences to select settings to verify the resolutions above, clicked back on "Default for display" and suddenly I got 4K@60Hz….
Best Answer
I don't know if this is a general answer or not, but this inexplicably worked for me....
The system seems very particular about what order things are plugged in. Here are the four ports of my laptop:
Back left <--> Belkin Thunderbolt 3 Dock <--> 5Bay TB2 HDD enclosure <--> Mini-Displayport to Dual-Link Display Adapter <--> 30" Cinema Display
Front left <--> HDMI cable to TV
Both right ports <--> None
If I plug the HDMI cable in first, it will connect/load and start displaying, sometimes at 30Hz and sometimes at 60Hz.
After it's displayed, I connect the dock and, during all the commotion of setting up the additional screen, it sometimes (or usually?) recognizes that 4K@60Hz HDMI is an option an uses it.
My best guess as to why? There may be a timing issue with the display discovery and this 4K display where the computer doesn't always think it has 60Hz available, but then, during the commotion, since the TV is already listening, the timing is better. But that's just a guess.