Does Dual-link DVI provide lower 'data-transfer latency' over Single-link?

There is a popular myth.. or reality.. I always wondered, what if i will connect Dual-Link DVI at 1920x1080? Does it ever produces any benefits over single link DVI connection? E.g. theoretically it have to has 2x more bandwidth and frame has to be transferred to my monitor 2x faster, over almost same electrical interface, which is just 2x wider. And IF (Sorry, I really do not know real specs, just for case) SL-DVI provides 1ms transfer lag, then do DL-DVI provide 0.5ms input lag? Am I correct in my assumptions?

xakepp35

Posted 2017-07-15T02:55:19.003

Reputation: 287

so far i saw from DVI wiki: Example display modes (single link): HDTV (1,920 × 1,080) @ 60 Hz with CVT-RB blanking (139 MHz) – xakepp35 – 2017-07-15T03:09:56.790

What does 139 mhz means? 139 mbit/s in terms of digital data transfer? – xakepp35 – 2017-07-15T03:10:35.253

wiki does not say.. 139 mhz of square wave? then why we do not choose a period of 1 bit==0.5ms, getting 2bits per hertz of electrical wave? (its not magnetical for sure) I am totally messed up with this :( Please help me, if i am total noooob – xakepp35 – 2017-07-15T03:19:28.853

How data transfer rates are formed? – xakepp35 – 2017-07-15T03:21:02.063

I'd be willing to bet that 1080p monitors only have DL-DVI connectors so that either kind of cable can be used. Now I want to take mine apart and check if those DL pins are connected to anything... – Jason – 2017-07-26T18:36:10.587

I think we're going to be in the realm of very little noticeable changes in the latency between the two flavors of the interface. – James Mertz – 2017-07-27T02:24:49.223

Answers

Does Dual-link DVI provide lower 'data-transfer latency' over Single-link?

No. At least, not in the sense that replacing a single-link cable with a dual-link one will change video latency.

DVI latency is set by the time it takes to transmit one frame. This is, in turn, set by the video frame rate. At 60 Hz, it takes 1/60 second (16.7 ms) to transmit one frame, so there's 16.7 ms latency in the link.

Some video resolution/framerate configurations may require a dual-link cable. For instance, a 2560x1440 monitor will require dual-link DVI to run at 60 Hz. However, every monitor also has a maximum resolution and frame rate, and most 1080p or smaller monitors do not require dual-link DVI to run under that maximum configuration. Using a dual-link cable will not make any difference for them.

duskwuff -inactive-

Posted 2017-07-15T02:55:19.003

Reputation: 3 824

Sounds strange, at least. It is more like - when you need to listen music and it's only mp3 320kbps - will your INTERNET CONNECTION BANDWIDTH go down from 1gbps to 320kbps, via LOWERING CARRIER frequency from 62.5Mhz to 0.02Mhz? NO! NEVER! its fairy tale ideas! So why does DVI does not just run at its maximum? It should transfer frame as fast as it possible. And then it could have some "free time", idling, not transfering anything at all, like in all normal data interfaces. Why DVI is so special, why does not it cares of latencies? And where can i read about it? Where did you get information? – xakepp35 – 2017-07-28T16:59:36.697

@xakepp35 The faster the link is, the higher the hardware requirements on the receiving end. And the monitor doesn't update all at once, either -- transmitting the frame data gradually matches the way the LCD uses the data internally. – duskwuff -inactive- – 2017-07-28T20:33:01.040

okay, now i got the point. thank you for useful strict answer! – xakepp35 – 2017-08-03T17:04:43.333

It's not a myth, but a reality.

The DVI link between a graphics card an monitor can operate at a bandwidth of 165MHz and no more. At 60Hz this leads to a maximum resolution of 1920x1080.

With dual-link DVI, a resolution of 2048 x 1536 is possible ( about 1.5x the number of pixels). Using 2560x1600 resolutions with PCoIP products (15134-1607) then 2x the number of pixels is possible with dual-DVI.

Tony Stewart Sunnyskyguy EE75

Posted 2017-07-15T02:55:19.003

Reputation: 1 582

So.. what's the relationship between latency and bandwidth? – user2813274 – 2017-07-15T03:24:55.910

I definetely saw that PCoIP picture.. it only defines common(!) layout of pinout for several video interfaces. And ye, i also wonder about relation between bandwidth and latency and this is the main question! Also where did you get 165MHz->2048 x 1536 conversion? Its also the point! What is MHz? MHz of WHAT? This is side question. How does that MHZ converts to mbits of data transfer and to latency! – xakepp35 – 2017-07-15T03:26:31.953

each DVI clock period there is a 10 bit symbol per channel. The set of three 10 bit symbols represents one complete pixel in single link mode and can represent either one or two complete pixels as a set of six 10 bit symbols in dual link mode. – Tony Stewart Sunnyskyguy EE75 – 2017-07-15T03:32:34.883

The dual channels add bandwidth but processing both channels may take some overhead depending on PLL's and pixel synchronization which affects resolution possible, and latency is negligible since the storage buffer is small. The frame and pixel rate the same . – Tony Stewart Sunnyskyguy EE75 – 2017-07-15T03:36:51.630

so 165 mhz is 165 million of hertz per 10bit transfer? Herts in somewhat unnamed value.. So its 16.50 mbits per second, so its 2.0625 mbytes per second, as programmer thinks of it. divided by 319201080, it gives me 0.347654 bits per pel.. so its nearly impossible!.. ah i forgot to multiply it by 60FPS, this is even lower value!!! – xakepp35 – 2017-07-15T04:00:43.723

There is no such thing as "triple-link DVI"… – duskwuff -inactive- – 2017-07-15T04:01:13.203

correct.(oops) future video ports are HDMI-2 will support legacy DVI but support higher resolutions and also the new DisplayPort 1.4 Standard, will support 8K video at 60Hz in 4:4:4 pixel format, and 120Hz in 4:2:0 format. – Tony Stewart Sunnyskyguy EE75 – 2017-07-15T04:22:22.073

So, what's about latency? – xakepp35 – 2017-07-17T15:54:53.530