Why can't monitors receive 120hz over HDMI?

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whitestar
Posts: 100
Joined: 12 May 2014, 06:11

Why can't monitors receive 120hz over HDMI?

Post by whitestar » 27 Oct 2015, 09:08

I asked this over at Anandtech, so I might as well ask here too. It's something I've just been wondering about after I had a look at the HDMI specs.

It seems since HDMI 1.4 it's possible to send 120hz over the HDMI cable, is that correct? Or was it 1.4b? So why can't monitors receive it then? Are they on 1.3 and lower? I realize that Displayport has become the standard, but still...

Side question: What is my GPU (GTX 670) sending? I looked at the specs on Geforce.com, but it just says HDMI, not which version. Or do graphics cards support all HDMI versions maybe?

Would be nice if someone could enlighten me. :)

Falkentyne
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Joined: 26 Mar 2014, 07:23

Re: Why can't monitors receive 120hz over HDMI?

Post by Falkentyne » 27 Oct 2015, 09:32

You need HDMI 2.0 to officially send 120hz over HDMI (at 1920x1080). 1.4 can only send *3D*.

RLBURNSIDE
Posts: 104
Joined: 06 Apr 2015, 16:09

Re: Why can't monitors receive 120hz over HDMI?

Post by RLBURNSIDE » 27 Oct 2015, 15:52

There is apparently a 2015 Sony UHD tv that accepts 2160p / 120hz using 420 chroma subsampling, which, if you know your maths, is exactly the same bandwidth as 2160p / 60hz RGB / 444.

This is for the same reason that NVidia could send UHD 60hz using 420 chroma over HDMI 1.4b videocards, which is the same bandwidth as UHD / 30 / 444, which is also the same as 1080p / 120 / 444.

I'm not sure what "officially" means, I think it's mostly dependent on what your display / TV will accept, rather than what your videocard can do which is plenty.

In theory you could use the same NVidia Kepler trick to send 2160p / 120hz / 420 using a Maxwell GPU. I think this depends on the EDID saying it accepts 120hz as well as the NVidia driver supporting it. Who knows, it might work. I can't see why Sony would release a 120hz TV if no current HDMI 2.0 video cards could drive it. Sony TVs are somewhat gamer friendly in terms of latency but not very HTPC friendly since they didn't support 444 at 60hz for their 2015 UHD Tvs. Although I read somewhere that Sony was updating the firmware on those TVs to accept 444 at 60hz too. Better late than never.

pneu
Posts: 27
Joined: 01 Mar 2015, 12:12

Re: Why can't monitors receive 120hz over HDMI?

Post by pneu » 29 Oct 2015, 20:13

It's 100% working with hdmi 1.4a on my R9 270. It's even listed in the monitor's manual.

Image

I also was able to overclock it to 144hz using CRU, but would get occasional picture dropouts.

Comanglia
Posts: 44
Joined: 13 Oct 2014, 16:06

Re: Why can't monitors receive 120hz over HDMI?

Post by Comanglia » 30 Oct 2015, 10:48

More than likely your monitor doesn't support HDMI 1.4 it's probably HDMI 1.3

Falkentyne
Posts: 2739
Joined: 26 Mar 2014, 07:23

Re: Why can't monitors receive 120hz over HDMI?

Post by Falkentyne » 30 Oct 2015, 10:52

pneu wrote:It's 100% working with hdmi 1.4a on my R9 270. It's even listed in the monitor's manual.

Image

I also was able to overclock it to 144hz using CRU, but would get occasional picture dropouts.
What monitor is this, that can handle [email protected] over HDMI on a PC?
Most that can do this are TV's (like some Vizio's and a few others that can accept a true 120hz signal).

the timing chart doesn't mean anything.
Most monitor chips are only capable of 60hz at 1920x1080 due to the actual HDMI chips used inside the monitor. The video card can handle it. it's what is used in the monitor that can't.

Q83Ia7ta
Posts: 759
Joined: 18 Dec 2013, 09:29

Re: Why can't monitors receive 120hz over HDMI?

Post by Q83Ia7ta » 30 Oct 2015, 19:18

Falkentyne wrote:What monitor is this, that can handle [email protected] over HDMI on a PC?
http://lmgtfy.com/?q=%22supported+timin ... A+DVI+HDMI#

Falkentyne
Posts: 2739
Joined: 26 Mar 2014, 07:23

Re: Why can't monitors receive 120hz over HDMI?

Post by Falkentyne » 30 Oct 2015, 19:47

Surprised that's not a Korean monitor. What with those things overclocking to 200hz and what not...
Wonder if this one will overclock to 200hz too.....any rich people want to buy one to test?

Or can the poster who has it try overclocking past 144hz on DVI? (you will need toastyX pixel clock patcher + 1098 VT reduced blank (vertical total)

pneu
Posts: 27
Joined: 01 Mar 2015, 12:12

Re: Why can't monitors receive 120hz over HDMI?

Post by pneu » 01 Nov 2015, 20:26

Falkentyne wrote:
What monitor is this, that can handle [email protected] over HDMI on a PC?
Yep, on my R9270 I ran 3 of them in eyefinity at 1080p120hz , 2 via DVI and the center monitor via HDMI. Which itself is a small miracle seeing as though the R9270 has to share a clock between 2 of the monitors :)

As I said I was also able to get 1080p144hz over HDMI but with occasional picture dropouts.

I didn't try overclocking past 144hz on DVI, and I don't have the monitors anymore so I'm sorry I cannot test it.

Q83Ia7ta
Posts: 759
Joined: 18 Dec 2013, 09:29

Re: Why can't monitors receive 120hz over HDMI?

Post by Q83Ia7ta » 07 Nov 2015, 09:05

Falkentyne wrote:Surprised that's not a Korean monitor.
It's Korean monitor but by Australian vendor. Just look at that case https://www.kogan.com/au/buy/kogan-24-l ... g-monitor/ same has Korean 24" monitors by QNIX & X-Star.

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