wacha wrote on 2020-02-20, 14:54:

I think I've been able to pinpoint the problem: the Single Link DVI 165 Mhz pixel clock limit. I have tested this forcing custom resolutions using Custom Resolution Utility 1.4.2. Anything beyond 165 Mhz Pixel Clock will make the image blurry and text unreadable. The connector is Dual Link, but I've since learned that half of the pins are dummies as HDMI is always Single Link and those extra pins are not connected to anything.

That's correct. DVI single-link and HDMI are electrically compatible, but beyond that, they are not.

wacha wrote on 2020-02-20, 14:54:

So my question is: can a DVI-D Dual Link output be converted to HDMI or Displayport? I've spent countless hours searching and reading misleading advertising and have only been able to find this: http://www.thruput.co.uk/home/product/videopr … g/GFVTCTLA.html

It will have to be this or something equivalent - an active converter.

wacha wrote on 2020-02-20, 14:54:

This situation leads me to believe that the cable might work, but I sincerely have no clue as to why it only does so in a single model of GTX 295. I've tried numerous driver versions, and it's always the same behaviour.

It's possible that that particular card has circuitry that knows how to output a high-clock HDMI signal on the single-link DVI connector pins, whereas the others do not. The card detects the monitor's capabilities during the handshake and switches on the fly to the required signal type. It's a similar idea to outputting an HDMI signal via the DisplayPort++ connector or an analog RGB (VGA) on the DVI-A connector. At least that's my guess.

Hi dr_st.

Thank you for your prompt and informative response. Your take on the Gigabyte GTX 295's "misterious" capabilities makes a lot of sense, my best guess would have been a VBIOS version (or witchcraft), but yours is definitely better. It makes me wish some of the other cards would be able to do the same thing though, as it would make matters much easier. If you allow me to request a little more of your time, would you happen to know any vendors or manufacturers that sell those kinds of active adapters? The only things I can find are the reverse converters (DP or HDMI to DVI) and terribly misguiding (or outright lying) ads for passive cables or dongles like the one I have. Amazon is especially ridden with the latter, and they always come up first when googling.

I still find it odd that the other two GTX 295 cards don't default to 1080p when first installing the drivers, but instead try to display 1440p and fail miserably. I mean, if I wasn't lucky enough to have the Gigabyte one, I wouldn't even be able to use those cards at all. None of the other cards I've tested behave that way. They even try to do 1440p, it's blurry and unreadable, but they don't just give up.

Visiontek made a DVI-D (digital only) to DP adapter cable that does 1440p.
https://www.visiontek.com/dvi-to-displayport- … -cable-m-m.html

Looks like you can order it from Amazon:
https://www.amazon.com/VisionTek-Products-Dis … e/dp/B0157RW0J4

Most older cards have DVI-I (digital + analogue) ports.

You may need a go-between such as a KVM switch.. look at the reviews on Amazon.

DVI-I just has extra pins, you can plug any DVI-D cable into a DVI-I port, but not the other way around.

edit:
I see what you mean by the amazon ratings... that is weird though, there should be no difference between the digital output on a DVI-I and a DVI-D port
maybe they tried using it on cards that don't support 1440p?

there is no such thing as a DVI-I digital signal, a DVI-I port just has additional pins that carry the analogue signal.

imi wrote on 2020-02-20, 18:21:

DVI-I just has extra pins, you can plug any DVI-D cable into a DVI-I port, but not the other way around. […]
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DVI-I just has extra pins, you can plug any DVI-D cable into a DVI-I port, but not the other way around.

edit:
I see what you mean by the amazon ratings... that is weird though, there should be no difference between the digital output on a DVI-I and a DVI-D port
maybe they tried using it on cards that don't support 1440p?

there is no such thing as a DVI-I digital signal, a DVI-I port just has additional pins that carry the analogue signal.

Yeah, I know. Doesn't make a lot of sense to me either.

It's most likely a typo - they either meant to write DVI-A or don't know the differences between DVI-I and DVI-A. In any case, I think their meaning is clear - the adapter can convert a digital signal, not an analog one.

Hi guys.

Thank you for your responses. Weird as it sounds, I don't think it's a typo. I mean, quotinq directly from the amazon seller's FAQ:

Q:the dvi end of this doesn't have the analog video pins present on a dvi-i port, so why wouldn't it work off the digital signal […]
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Q:the dvi end of this doesn't have the analog video pins present on a dvi-i port, so why wouldn't it work off the digital signal in a dvi-i port?

A:The wiring is not set to support DVI-I. This unit simply was not manufactured to support it.

R:Then you need to change this misleading part of the description "DVI-I Analog signal is not supported. " which conflates the signal output with the port type.
At minimum, it should read: "Digital signal output from a DVI-I port is not supported. "
To be more unequivocal, change the entire line to read as follows:
"Supports DVI-D ports only. Digital signal output from a DVI-I port is not supported. "
And be sure to fix it on your website (https://www.visiontek.com/dvi-to-displayport- … -cable-m-m.html) too.
If you had done that, or if your support department had responded to the email I sent before I bought this (which even now they still have not done), I wouldn't have to return it now.

And from one of the reviews:

Ironically, in my case it did work just well enough on the *digital* signal from a DVI-I port to make me think there was a software issue: it did allow a 2560x1440 monitor to run at 1080p (from a video card capable of 2560x1600). After an email to Visiontek's tech support went unanswered for several days, resulting in many hours of troubleshooting trying to determine if different video card driver software was needed to get the monitor's native 2560x1440 res. (without any success), I finally got the answer from Visiontek: this cable does not work correctly with DVI-I *digital* signal either.

Which sounds exactly like the problem I'm having with the passive cable. Is there even such a thing as an "active cable"? Don't active converters have a separate cable that draws power from a USB port or directly from the wall? It just looks like the cable I bought from Amazon Basics, but 5 times more expensive. Now that I think of it, I believe I haven't tried my cable on a GPU with a DVI-D connector. I'm going to test it with a 780Ti that I got lying around and report back.

Come the worst, do you have any ideas on how I could make this a two step process? Would a KVM Switch work, like suggested above?

Thanks guys, we might even learn something from this.

The ones with the USB power are going from DP output to DVI input. Something about the DP port not being able to output enough power to power the active converter.

If you look at the Visiontek site, that adapter cable does have a converter device in the middle of the cable so it isn't just a passive cable.

wacha wrote on 2020-02-20, 20:53:

Hi guys.

Thank you for your responses. Weird as it sounds, I don't think it's a typo. I mean, quotinq directly from the amazon seller's FAQ:

I know that is what it says... but this should not be possible, unless they really messed up something in the design process and somehow made it so that anything on pin 8 of the connector breaks functionality of the device, since that is the only pin that is on the DVI-D part of the connector that has an analogue signal... but even then, there should be nothing on that if setting DVI to a digital output.

but now that I think of it... I remember having a weird issue with a LCD before, that would not work in digital mode with a DVI-I cable... that probably had some detection method to recognize a DVI-I connection and did not switch to digital, but why they would build a DVI to DP adapter like that is beyond me, in any case I think this is a mess up on their part and they don't want to admit it.

Ok, so I've tested the 780Ti and....it works out of the box. It works using both the DVI-D port and the DVI-I port, so now I'm really confused. If it were a port incompatibility it should not work when connected to the DVI-I port. If it were a bandwidth issue it should never be able to output 1440p 60Hz, but it's happy to do it. Damn, this shouldn't be so difficult, but I'm completely puzzled. Another "special" card like the Gigabyte GTX 295 or are we missing something here?

If you look at the Visiontek site, that adapter cable does have a converter device in the middle of the cable so it isn't just a passive cable.

True that, my bad.

I know that is what it says... but this should not be possible, unless they really messed up something in the design process and somehow made it so that anything on pin 8 of the connector breaks functionality of the device, since that is the only pin that is on the DVI-D part of the connector that has an analogue signal... but even then, there should be nothing on that if setting DVI to a digital output.

I know. Nothing makes sense here. We must be missing something...

Hi again.

I've been conducting further testing for most of the afternoon and I've made some progress. At first I was trying to make the conversion work with an HD 3870 X2. No success there. Then I've remembered that during my countless searches I stumbled upon two little patchers for AMD and Nvidia drivers that claimed to remove the pixel clock limit. It seemed like a new line of investigation. So I plugged in one of my HD 7990s (DVI-I) and got to work. Default behaviour was as expected, 1080p 60Hz max resolution and the inability to show 1440p 60Hz correctly. But after running the patcher and rebooting, voilá, 1440p 60Hz by default with flawless, crisp image!

So I think this rules out the cable. With the 7990, it's now doing 1440p with 4 different configurations: one GTX 295, both my GTX 590s, my 780Ti and both my 7990s. That leads me to believe that the passive cable can actually do as advertised just fine, and that we might be dealing with a software issue. Now there's a few caveats here. Firstly, these patchers only work on HD 5000 series or newer cards from AMD or GTX 400 series or newer from Nvidia. Secondly, I only have a limited selection of cards fitting those requirements, so I cannot test that this works for every card or combination of cards. And lastly, there are some inconsistencies in the original behaviour of the cards, and we still have one card, the Gigabyte GTX 295, that works out of the box when it shouldn't, if this were a software only issue.

The ideal solution is still a DVI-I to HDMI or DP 1440p adapter/converter/scaler. Should that be possible, there would be a consistent, out of the box way of achieving 1440p across all GPUs pre-HDMI 2.0 and DP era. This workaround will at most allow someone with a setup like mine use a small selection of generations - GTX 400, 500 and 600 series from Nvidia and HD 5000, 6000, 7000 from AMD. Anything newer than that will have ample support for newer standards. Anything older is not supported by the patch. I've tried the patch on the 3870 X2s and it doesn't work. It could even be a more constrained of a selection, as both my 7990s sport 4 mini-DP connectors and I'm just using the DVI port for convenience and not having to use 700 different cables.

Does this new finding give you any ideas? I feel like this should be much easier than what I'm making it, but I'm running out of ideas. I need to test the patch with the 590s and see if it works too, for the sake of consistency.

ATI/AMD Patcher

Nvidia Patcher

Thank you.

This is interesting. If I understand correctly, you are basically overclocking the DVI link itself? By how much? I wonder if the circuitry can withstand it for long periods of time.

dr_st wrote on 2020-02-22, 07:54:

This is interesting. If I understand correctly, you are basically overclocking the DVI link itself? By how much? I wonder if the circuitry can withstand it for long periods of time.

That's what I make of it. I asked for help on the CRU forums but we haven't been able to understand the inconsistencies in the behaviour of the cards. I was recommended this: https://www.gefen.com/product/dual-link-dvi-m … GTV-DVIDL-2-MDP

It seems like it would do the trick, and the reviews suggest that it works as intended, but it's very expensive. I'm a spaniard, and I can only find sellers in the USA, so if I add the cost of the device, shipping, customs and VAT, I'm looking at about 250€. I might take one for the team and buy it, as it is cheaper than a new comparable monitor (32 inch, 1440p, 144Hz, curved) and I don't have space for two monitors as of now. I don't even think there's a monitor with VGA, DVI, DP and HDMI support and at least the aforementioned characteristics in the market, whatever the price.

In the meantime, I'll let you know if I find any alternative. If someone has a suggestion or something to test, please write it here. I would especially like to understand this inconsistent behaviour when the only thing that changes is the GPU. Same monitor, same OS, same motherboard, RAM, CPU, same adapter cable...

Thank you.

Here is an Atlona unit that should do the same thing.
ATLONA AT-DP400

Maybe that one is available closer to where you are.

Looks like there are a few on eBay. This unit has been discontinued by Atlona.

cyclone3d wrote on 2020-02-25, 16:52:

Here is an Atlona unit that should do the same thing. ATLONA AT-DP400 […]
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Here is an Atlona unit that should do the same thing.
ATLONA AT-DP400

Maybe that one is available closer to where you are.

Looks like there are a few on eBay. This unit has been discontinued by Atlona.

Thank you. It seems the only sellers are from the States as well...but it is a bit cheaper. I think I'll buy it, after looking thoroughly for other options and/or sellers.

I've been given some very useful info at the CRU forums from the developer himself, ToastyX. I quote:

The behavior will depend on whether it's treated as DVI or HDMI. […]
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The behavior will depend on whether it's treated as DVI or HDMI.

Newer cards will output an HDMI signal over DVI ports if HDMI support is defined in the extension block. Older cards might only output DVI no matter what.

If it's treated as DVI, you will get a blurry image beyond 165 MHz pixel clock because that's where it switches to a dual-link signal, but HDMI is single-link, so you lose half the pixels. Renaming the patcher to whatever-patcher-single.exe will make it always send a single-link signal, but that might not work with older cards.

If it's treated as HDMI, AMD/ATI cards will output an HDMI signal over DVI ports, but only up to 165 MHz pixel clock unless the driver is patched. With the HD 7990, you shouldn't need the patch if you plug the monitor directly into an HDMI port.

NVIDIA cards will output an HDMI signal over DVI without the 165 MHz limitation, but keep in mind older cards might not have the hardware to handle higher pixel clocks because old versions of HDMI only supported up to 165 MHz. The one GTX 295 probably has a better TMDS transmitter that is capable of higher pixel clocks.

It's been a while, but I just ordered this one. It might fit your needs as well .

https://www.cablematters.com/pc-825-139-gold- … z-in-black.aspx

EDIT: I got it for 40$ Canadian .
EDIT : Misread your needs . That Gefen thing seems like the only option for your needs .