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d5aqoëp

macrumors 68000
Original poster
Feb 9, 2016
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Right now, Sierra 10.12 supports HDMI 1.4b which maxes out 4K @ 30 Hz only. If we switch to 60 Hz, the screen becomes blank. So it becomes impossible to connect a 4K TV externally and use it as a monitor.
 
Right now, Sierra 10.12 supports HDMI 1.4b which maxes out 4K @ 30 Hz only. If we switch to 60 Hz, the screen becomes blank. So it becomes impossible to connect a 4K TV externally and use it as a monitor.

Not sure as I haven't tried it yet, but it seems to be a limitation with USB-C. There's several adapters being marketed that solves this problem via DisplayPort alt mode you might be interested in.

http://www.businesswire.com/news/ho...chnologies-Enables-VESA-Certified-USB-C-HDMI™

And

https://9to5mac.com/2017/05/17/accell-usb-c-hdmi-2-0-4k-60hz-review-video/

I know it's not the answer that you're looking for, but I hope it helps.
 
Gah! Your "issue" lies in not using the correct adapter/converter, that's all, and you're about US$40 away from addressing that issue. Two bits about benthewraith's post, the helpful and the "uh, what?". The latter - it's not a "USB-C" issue, for me hearing something like that is like the good ol' standby "I have a Bluetooth!"; USB-C is a port/connector configuration name, that's all it is.

Watch that video, but pause it at 13 seconds and read those specs. Note the words "compliant" and "compliance" - they're relevant here, and very helpful. Also note the "Windows" bit at the top - ignore that as Accell has updated the product and its web page to include Macs and HDMI 2.0a (which adds HDR). Back on point, Accell is one of the few companies I have purchased from that adheres to specs, including the DisplayPort specs (Eizo, Belkin, and StarTech are a few others that do as well). I suggest sticking with companies that make compliant problems, or you can search these forums for my comments on this matter…

That type of adapter converts the embedded DisplayPort signal to an HDMI signal, including EDID or DisplayID/video/sound and has nothing to do with DisplayPort Alternate Mode - they don't carry or convert any SuperSpeed data. Adapters that perform this have been around for a few years now, before USB-C was on the market.

That linked-to short review is simply a DisplayPort signal to HDMI signal converter with the relevant port connections on each end, that's it. Accell makes a Mini DisplayPort 1.2-to-HDMI 2.0 active adapter, I've got several in my offices, attached to BenQ 4k displays (BL2711U), and they work perfectly with Windows and Macs:
https://www.accellcables.com/collections/adapters/products/mini-displayport-1-2-to-hdmi-2-0-adapter

Accell simply updated the converter in the reviewed adapter, and I suspect they'll be one of the first to have a HDMI 2.1 adapter on the market later this year or at CES next year. Find the suitable DP-to-HDMI 2.0 adapter and that should address what you want…
 
Right now, Sierra 10.12 supports HDMI 1.4b which maxes out 4K @ 30 Hz only. If we switch to 60 Hz, the screen becomes blank. So it becomes impossible to connect a 4K TV externally and use it as a monitor.

That statement is not correct. I have a 4K TV and a 2016 MacBook Pro and I run my TV at 60Hz. Perhaps it depends on your hardware.
 
That statement is not correct. I have a 4K TV and a 2016 MacBook Pro and I run my TV at 60Hz. Perhaps it depends on your hardware.
That is because you are running your TV off USB-C port of MacBook pro with adapter.
But If you use an iMac or eGPU or even a hackintosh which has discreet HDMI 2.0 port like Nvidia 9XX and 10XX series and Radeon 4XX and 5XX series, 4K @ 60 Hz is not possible after directly connecting the GPU's HDMI 2.0 port to your 4K TV's HDMI port.

The only 2 working solutions
1. USB-C port -> HDMI Dongle Adapter -> 4K TV (Works but most PCs/macs don't have Thunderbolt USB-C port) This also puts tremendous strain on punny integrated GPU of MBP.
2. Display Port 1.2 -> DP 1.2 to HDMI 2.0 active Adapter -> 4K TV (Blank screen but works after hot plugging)

GPU HDMI 2.0 port -> HDMI 2.0 cable -> 4K TV (4K @ 30 Hz Max)
 
Nah, that list isn't complete. My late-2013 rMBP isn't on the supported list for 4k @60Hz, but my laptop pushes that - on two Dell 4k displays @ 60Hz at the same time (plus the built-in display at full res)… So, nah.

Ok. I have 4k OLED-TV as a monitor.
 
Ok. I have 4k OLED-TV as a monitor.
The part I called out in Post #3 should work fine. My small company has several 4k TVs in use for presentations, most with HDMI 2.0. The Accell adapter works perfectly - 2160p @ 60Hz. QED.
 
Well, High Sierra 10.13.0 also does not allow 4K @ 60Hz via HDMI 2.0 using Nvidia’s latest drivers. So our OLEDs are useless on macOS and we have to be at the mercy of Club3D adapter which converts DP1.2 to HDMI. But the problem with that adapter is macOS boots to blank screen with it is plugged in. We need to hot plug it everytime AFTER macOS has finished booting.
LMAO!
 
I have old Mac Pro from 2012 and 4K screen HP Z27s. I have changed the graphic card to an NVIDIA GeForce GTX680 2048MB. When I connect the screen with displayport/minidisplayport I get no boot screen, the screen is black until the log in-window. Then it works in 4K, but I see no improvement of image quality compared to when I had the ATI Radeon HD 5770. When I use HDMI-cable 1.4 4K I get boot screen, but then it only gives 30 Hz and the flickering around windows is back. Even if I chose 2560x1440 it only gives 30 Hz. The computer is hotter now then before and the fans are spinning much faster. Is this computer finished more or less? I recently shipped an MacBook Pro 17" 2011 to the recycling station due to graphic card problems. I was near to do the same with this Mac Pro earlier this autumn but I kept it.
One more thing: When I look at tv-shows on for example www.svtplay.se the image quality is very bad. The best image quality I nowadays have in my smart phone, LG G4. There you have excellent picture all the time!
 
Does someone know whether it is possible to get my external monitor working with my 15" MacBook Pro (2017) running MacOS High Sierra 10.13?

I used to have a 2016 model running Sierra and used a USB-C to DisplayPort adapter to connect my MacBook Pro to my external monitor, and this worked fine.
However, now all of a sudden on my 2017 MacBook Pro running High Sierra, the display is not being recognized anymore.

I have a Philips UHD monitor, I think it can display at 60 Hz max., but there seems to be no way to change it.
Does that mean that, even if I would purchase myself a USB-C to HDMI adapter, I would still end up with a blank screen? Is there an adapter that will actually work?
 
dthrys wrote:
"I used to have a 2016 model running Sierra and used a USB-C to DisplayPort adapter to connect my MacBook Pro to my external monitor, and this worked fine.
However, now all of a sudden on my 2017 MacBook Pro running High Sierra, the display is not being recognized anymore."


If it worked with the 2016 but NOT WITH the 2017, it's almost certainly the cable that you're using.

Some cables work fine with the 2016's, but NOT with the 2017's.

You need to go somewhere like amazon, and then CAREFULLY CHECK OUT the cables that are available, and find one that is SPECIFICALLY STATED to be compatible with 2017 MacBook Pro's.

Check the product descriptions, but ALSO check user reviews and Q&A's to see reports of actual user experiences...
 
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here's how i got passed 30hz in 4k on my Sierra hackintosh.

tl;dr - I upgraded the firmware on my CAC-1070 DP/HDMI converter, installed switchresx, defined a custom resolution @ 60hz, then (most importantly) turned my 4k screen off and on

my setup:
hackintosh Sierra 10.12.6
geforce gtx 1070 - most updated web drivers (378.05.05.25f04)
primary display - Sceptre U425CV-UMC (budget 4k), connected via CAC-1070 DP/HDMI adapter
secondary display - Lenovo LI2364D, connected via HDMI


so I've been struggling getting 2560x1440 @ 60hz. Everythime i tried anything over 1080, my main screen would generally just go blank and become unusable even after reboots. i'd have to wipe display plists and/or shuffle around hdmi connectors & ports on the back of the computer. It worked fine in Windows, so it just didn't make any sense why it didn't on my mac install.....

After much frustration, trial and error, this is what finally worked for me

0. modify SMBIOS to have the OS (snowflake warning) self-identify as an iMac17,1 (not sure if this step is even necessary)

1. upgraded the firmware on the cac-1070 connector. follow instructions here
http://insights.club-3d.com/thread/cac-1070-firmware-download/

2. install switchresx; do not reboot. load up a custom resolution of 3840x2160 using the 'simplified settings' of CVT-RB. if the scan rate doesn't auto-populate, manually enter 60hz. save settings. reboot.

3. so after this reboot, my primary display went completely dark and the OS didn't even recognize it. the simplest yet most important step comes here. turn off / turn on the display. it was recognized by the OS at the default 4k / 30hz, so i then switched to the 4k/60hz custom setting in switchresx. from there i repeated step 2 to implement 2560x1440 @ 60hz.

4. Done, son.

so now, the only thing that's a bit annoying is that i have to turn off / turn on the display every time i boot into the hackintosh. The OS still has a hard time seeing the 4k display even from a cold boot. a little strange but at this point, i'll take it.

anyway, hope this helps others who have been struggling with the same....now if you'll excuse me, i'm leaving to bask in the 4k/60hz glory....
 
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