MP 7,1 Is 120hz possible via HDMI 2.1 on 6900xt card?

[RyanFlynn]

Hey friends,

I'm picking up a Mac Pro tower tomorrow, switching from pc. I'm LOVING 120hz and know it will be hard to go back to 60. This card has HDMI 2.1, if I put it in my Mac Pro, will Mac OS support 120hz via HDMI into my LG cx?

Thanks!
Ryan

 

[h9826790]

I can't see why not, the HDMI port on my Radeon VII can deliver 120Hz in macOS without any issue.

 

[LEOMODE]

Reviving this as I just got my LG 950GP with HDMI 2.1 capability. But when I hook it up to Big Sur 11.6 on AMD 6900XT HDMI 2.1 port, the highest Hz I'm seeing is 60hz.

Big Sur killed DSC 1.4 DP support for 120hz also, so I am pretty sure Big Sur is the issue here, as I have no problem on Boot Camp Windows 10 outputting 4k 120hz. I'm wondering if Apple is trying to kill other non-Apple support and only make it compatible with Apple-sold hardware which is terrible.

 

[h9826790]

Reviving this as I just got my LG 950GP with HDMI 2.1 capability. But when I hook it up to Big Sur 11.6 on AMD 6900XT HDMI 2.1 port, the highest Hz I'm seeing is 60hz.

Big Sur killed DSC 1.4 DP support for 120hz also, so I am pretty sure Big Sur is the issue here, as I have no problem on Boot Camp Windows 10 outputting 4k 120hz. I'm wondering if Apple is trying to kill other non-Apple support and only make it compatible with Apple-sold hardware which is terrible.

Did you try ResXtreme or SwitchResX

 

[RyanFlynn]

Reviving this as I just got my LG 950GP with HDMI 2.1 capability. But when I hook it up to Big Sur 11.6 on AMD 6900XT HDMI 2.1 port, the highest Hz I'm seeing is 60hz.

Big Sur killed DSC 1.4 DP support for 120hz also, so I am pretty sure Big Sur is the issue here, as I have no problem on Boot Camp Windows 10 outputting 4k 120hz. I'm wondering if Apple is trying to kill other non-Apple support and only make it compatible with Apple-sold hardware which is terrible.

Yeah, and if you buy the MPX modules from apple, the HDMI out is only 2.0 instead of the 2.1 included with pc versions of the cards (that cost 75% less)

I had to switch back to the Mac Pro for work, while I love the OS, I really miss 120 hz.

 

[LEOMODE]

Did you try ResXtreme or SwitchResX

Thanks. Just opened up SwitchResX and this is what I'm seeing for the DisplayPort.

For the HDMI port, this is what I'm seeing in the 2nd attached file. Looks like 144hz and 120hz are visible but not at retina resolution.

For ResXtreme this is what I'm seeing in the attached files for both outputs.

Any other insight will be very helpful. Thanks.

 

[h9826790]

Thanks. Just opened up SwitchResX and this is what I'm seeing for the DisplayPort.

For the HDMI port, this is what I'm seeing in the 2nd attached file. Looks like 144hz and 120hz are visible but not at retina resolution.

For ResXtreme this is what I'm seeing in the attached files for both outputs.

Any other insight will be very helpful. Thanks.

HDMI 2.0 can do 144Hz, but only up to 2560x1440 (non HiDPI).

If you want to do that at 4K (or any HiDPI resolution between 1920x1080 and 3840x2160), then you can only do 120Hz with 4:2:0 subsampling.

I missed the fact that my monitor is a 3840x1080 monitor, therefore, can do 120Hz with no restriction even with just HDMI 2.0

 

[LEOMODE]

HDMI 2.0 can do 144Hz, but only up to 2560x1440 (non HiDPI).

If you want to do that at 4K (or any HiDPI resolution between 1920x1080 and 3840x2160), then you can only do 120Hz with 4:2:0 subsampling.

I missed the fact that my monitor is a 3840x1080 monitor, therefore, can do 120Hz with no restriction even with just HDMI 2.0

Thanks for your reply. Can I do 120hz with 4:2:0 subsampling using either of those 2 programs? I can't seem to find it.

 

[LEOMODE]

Updated to Monterey, still same 95hz only. Still desperately waiting for @h9826790's response on resolving this issue

 

[h9826790]

Thanks for your reply. Can I do 120hz with 4:2:0 subsampling using either of those 2 programs? I can't seem to find it.

AFAIK, no.

You have to manually edit the EDID to get that.

 

[LEOMODE]

AFAIK, no.

You have to manually edit the EDID to get that.

Thanks how would I be able to do that?

 

[LEOMODE]

AFAIK, no.

You have to manually edit the EDID to get that.

Reviving this thread as I’ve got an HDMI 2.1 cable that outputs 4k 120hz and 8k 60hz. However, this only outputs 60hz but does give me an option for HDR.

Snowkids 10K 8K HDMI Cable 2.1... https://www.amazon.com/dp/B099ZRBW2N?ref=ppx_pop_mob_ap_share

Interestingly, the LG 4k 144hz monitor outputs 120hz fine but does lose HDR in either a DisplayPort (using dp to HDMI adapter) or HDMI input in the 6900xt.

Cable Matters 8K DisplayPort 1.4... https://www.amazon.com/dp/B08XFSLWQF?ref=ppx_pop_mob_ap_share

Now I have 2 questions in mind when on Mac OS Ventura:

Why is my LG cable capable of 120hz with no HDR?
Why is an 8k60hz HDMI 2.1 advertised cable only capable of 60hz with HDR?

Any experienced people/input will be greatly appreciated.

 

[LEOMODE]

So I noticed that my HDMI cables (Snowkids) were fine. I switched it around with LG cables, and it looks like 6900XT ports at Displayport only accepts 60hz with HDR (by using Cable Matters one stated above). Only HDMI port with either of HDMI cables will accept 60hz with HDR or 120hz. Not sure why they would do this. My HDMI to DP cable supports 4k @ 120hz...USB-C port on 6900 XT works the same as DP port.

I'm not understanding this correctly.

Just FYI if you connect DP to DP, you still only get 95hz maximum at this thing (with no HDR). Mac OS really needs to update this limitation.

 

[ZombiePhysicist]

Did you try ResXtreme or SwitchResX

What is ResXtreme. I searched but found it only on shady 'download' sites.

 

[h9826790]

What is ResXtreme. I searched but found it only on shady 'download' sites.

That's a very old apps now. May be the official site is already down.

Nowadays, you may try BetterDisplay, even the free version is already quite powerful.

GitHub - waydabber/BetterDisplay: Unlock your displays on your Mac! Flexible HiDPI scaling, XDR/HDR extra brightness, virtual screens, DDC control, extra dimming, PIP/streaming, EDID override and lots more!

Unlock your displays on your Mac! Flexible HiDPI scaling, XDR/HDR extra brightness, virtual screens, DDC control, extra dimming, PIP/streaming, EDID override and lots more! - waydabber/BetterDisplay

github.com

 

[LEOMODE]

Reviving this again. Sonoma 14.1.2 and still the same issue. HDMI to Displayport still only outputs 4k 60hz with HDR, but if I do HDMI to HDMI on my 6900XT it outputs 4K 120hz without HDR.

On Windows 11, all of them goes fine with 4k 120hz WITH HDR.

This is very unfortunate.

 

[RyanFlynn]

At this point, I'm guessing apple is going to release a 120hz Pro Display or something. They want it to feel new and inventive.

 

[LEOMODE]

So sad as in my triple monitor using Mac OS, I'm doing 4k 120hz on one monitor and 60hz on the other 2...also it sucks because when I turn on HDR on 4k 120hz, it goes down to 60hz. Very annoying because now I can't go back to the 60hz refresh rate lol, the only way is to use DP but still only gives me 90hz max, whereas in Windows Boot Camp I get full 4k 144hz.

 

[thirdhonk]

I have a 6950 XT reference card in my 7,1. I flashed it to a 6900 XT, it benchmarked the same before and after which is why I went the flash route. I flashed it from Windows 11 in bootcamp, no issues.

Anyway I get 4K 120Hz over HDMI 2.1 from the 6950 XT to my LG C3 OLED in both the latest Sonoma update and Windows 11, I'm almost certain HDR works with both as well. I don't see why it wouldn't work on a normal 6900 XT, I have one in my 5,1 I could try as well. I did have to enable some settings on the TV for it to work but can't recall what.

I also have a Macbook Pro M3 Pro which has HDMI 2.1, it also works fine in 4K 120Hz.