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Damian83

macrumors regular
Original poster
Jul 20, 2011
211
118
hi, i'm just upgrading my imac and macbook and now ill also have to upgrade all accessories with TB3. first of all ill buy an tb3(usb-c) to hdmi adapter and here the confusione begins. does really tb3>hdmi adapters exists or they are all usb-c>hdmi? some retailers says 10gbps 4k/30fps while other says only 4k/60fps. the first (10gbps 4k/30fps) seems a real value as usb c 3.1 is 10gbps and hdmi 1.4 its 4k/30fps@10gbps. while the 2nd (4k/60fps) seems a ******** because in order to reach this res we need 18gbps and usb-c 3.1 isnt enough. tb3 (or even tb2) its mandatory in this case, but there's also wrote that those adapters works in both only usb-c and tb3 ports. even the belkin adapter on apple store its unclear how works because it's named USB-C to HDMI adapter but in the specs its "Thunderbolt 3 (USB-C)". any tips?
 

Fishrrman

macrumors Core
Feb 20, 2009
22,991
8,756
For a 4k display @60hz, you need to be careful about which cable/adpater you get. Some research is involved.

I believe the keywords you should look for are
- usb-c
- 4k
- HDMI 2.0 (important)
- 60hz (important)

Also -- once you get the choices narrowed down, take the time to read the user reviews and see how Mac users fared with the product.
 

Damian83

macrumors regular
Original poster
Jul 20, 2011
211
118
first of i need an adapter (female-hdmi, male-usb) not a cable with hdmi-male and usb male, so no one writes about hdmi spec (1.4 or 2.0). fact is that i found several usb-c (no tb3) adapters that supports 4k@60 and i dont know how it is possible. usb-c is 10gbps while 4k@60 its hdmi 2.0 and hdmi 2.0 is 18gbps. i also found REAL TB3 adapters but they are with dual hdmi and works at max res (x2) only if connected in tb3. if connected on a usb-c then max res supported is 1080p (x2)
 
Last edited:

chrfr

macrumors G4
Jul 11, 2009
11,197
4,766
first of i need an adapter (female-hdmi, male-usb) not a cable with hdmi-male and usb male, so no one writes about hdmi spec (1.4 or 2.0). fact is that i found several usb-c (no tb3) adapters that supports 4k@60 and i dont know how it is possible. usb-c is 20gbps while 4k@60 its hdmi 2.0 and hdmi 2.0 is 18gbps. i also found REAL TB3 adapters but they are with dual hdmi and works at max res (x2) only if connected in tb3. if connected on a usb-c then max res supported is 1080p (x2)
USB-C as implemented in all current shipping Macs offers no more than 10Gbps. Nonetheless, USB-C to HDMI adapters work fine at 4K/60Hz; there’s no need for a true Thunderbolt adapter. I’ve installed many of these: https://www.anker.com/products/variant/usbc-to-hdmi-adapter/A8306041 and they work as advertised at 4K/60.
This also works, but it’s overpriced:
Belkin USB-C to HDMI Adapter

 

thunderstruck

macrumors newbie
Oct 20, 2019
15
8
Sydney Australia
From my limited research, it appears that only a dedicated USB-C to HDMI 2.0 adapter or a Thunderbolt dock will work at 4k@60 (the dock obviously has to state that it supports 4k@60). Both of these solutions work because they rely on active conversion from a DisplayPort signal to a HDMI signal using a small chip in the adapter or dock. In other words, 4k@60 requires an active adapter.

I ended up getting this adapter:

StarTech USB-C to HDMI adapter HDR 4K 60Hz

because it's a well known brand, has a 3 year warranty, and is marketed as suitable for use by Macs. Yes it's a bit more expensive than other adapters (about $30) but StarTech products tend to be well made and last longer than the warranty period. I have previously bought a cheap no-brand USB-C to HDMI adapter (probably passive) but it only worked well with a 2k monitor and always failed to display on a TV. Once bitten, twice shy.

I've used the StarTech adapter from a MBP 15" 2017 to 2 different FullHD (2k) TVs (one directly and one through a receiver) and it worked fine with both of them. Interestingly, the Samsung TV required overscan adjustment but the Sony TV did not. I don't have a 4k TV or monitor. Because it's an active converter, it does get warm when used but not super hot. It worked fine from both macOS 10.14.4 and Windows 10. I don't expect any problems with using it on a 4k TV when I later upgrade because I trust this brand and the review on the Amazon listing states that 4k@60 works.

BTW, this adapter was released in late 2018 despite what the Amazon listing states. That's one of the reasons I chose it: it's recent enough to have a newer converter chip in it which hopefully avoids compatibility problems in older chips.

There's also information on StarTech's website.

One final wrinkle: if you want to output HDR from a Mac using this adapter, it looks like you'll need a 2018 or later model because earlier models don't support DisplayPort 1.4. However, the linked article does not make it clear whether using this adapter will work from a Mac to an HDR-capable UHD TV.

An added bonus: I can use this adapter to watch HEVC/HDR/BT.2020 encoded video on an SDR TV! It looks like macOS can convert an HDR/BT.2020 image to SDR/BT.709 which the TV then displays. Before this, I could only watch HDR video on the MBP screen but I prefer the larger TV so this was a nice bonus. :)
 
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assoc

macrumors member
Jul 14, 2013
56
5
If I wanted to connect an HDR 4k60 monitor via USBC to Displayport instead, would I still need an adaptor or would a cable like this work?
 
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