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Author Topic: when is a cable not a cable - when it's a DVI-D  (Read 4961 times)

nudone

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when is a cable not a cable - when it's a DVI-D
« on: August 19, 2011, 02:15:44 AM »
I'm really getting tired of computers; hardware if nothing else. I simply wanted an extension cable so that I can place the monitor about 3m away from the pc.

Apparently this is just too demanding of me. The universe (or the pc hardware subset, at least) has decided that I am not allowed to have a graphics card's digital signal traverse such incredible distances of 300 centimeters.

So, can anyone enlighten me as to why a DVI-D cable that is 2 meters works perfectly well (the one that came with the monitor), and a 3 meter DVI-D cable I've just purchased doesn't work at all?

The connections, i.e. number and shape of pins, that each cable has are identical - but I'm obviously a fool and can't see the blindingly obvious differences. Maybe the one that works has 10,000 angels sitting on the head of each pin (or whatever the phrase is). Somehow I need these angels to migrate over to the new 3 meter cable's pins.

Honestly, I'm just sick to death of hardware not working. This is just a DVI-D cable, how simple a piece of hardware can that be.

As a caveat: I am connecting to a 30" monitor (2560 x 1600) but I don't see why that should be an excuse.

p.s.
Yep, I've tested the 3m cable and it works perfectly well with a lower resolution monitor (1920 x 1200).
« Last Edit: August 19, 2011, 02:22:01 AM by nudone »

cranioscopical

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Re: when is a cable not a cable - when it's a DVI-D
« Reply #1 on: August 19, 2011, 02:48:06 AM »
And does the 2 meter cable still now work with the 30"?

Looks as if you might need a repeater.

You're not having much fun with this machine, are you?  :(

nudone

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Re: when is a cable not a cable - when it's a DVI-D
« Reply #2 on: August 19, 2011, 02:55:01 AM »
And does the 2 meter cable still now work with the 30"?

Yep. The 2 meter one is fine but that came with the monitor and looks kind of "special". It looks a lot beefier than other DVI cables and has lime green coloured plugs - maybe they are made of Kryptonite.

I've also found someone else online stating they've had the same problem - only the cable that came with the monitor works (2 meters).

Can't find anyone claiming they've got a 3 meter cable to work with a 2560 x 1600 resolution screen.

Plenty of 3m cable product descriptions saying they will work at that res - but I can't say I trust them.

Maybe a repeater is the answer - but, again, I'm not sure I trust the claims unless it's from someone that has such a thing working for their own setup.

4wd

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Re: when is a cable not a cable - when it's a DVI-D
« Reply #3 on: August 19, 2011, 03:21:59 AM »
The higher the resolution the more pixels that have to be pushed out and thus a higher transmission rate down the cable, (if you're intending to keep the same refresh rates).

The construction/quality of the cable is a major factor in whether it will work at a higher frequency, eg. thinner conductors or high percentage of contaminants in the materials will cause greater attenuation at higher frequencies.

If where you bought it, specified that it supported 2560x1600, (as this one does), and it didn't work then you'd be fully justified in getting a refund/replacement.

Here's a company in the UK advertising 3 and 5 meter cables that will work up to 2560x1600.  They're also available in a 25 meter length if you want to put the monitor next door.

EDIT: Just realised, make sure you get a DVI-D Dual Link cable.  DVI-D Single Link is restricted to 1920x1200.
« Last Edit: August 19, 2011, 03:37:38 AM by 4wd »

nudone

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Re: when is a cable not a cable - when it's a DVI-D
« Reply #4 on: August 19, 2011, 03:36:31 AM »
Good point. And, I am an idiot - it's official.

I did get the 3m cable via eBay, taking a bit of a chance and not spending much, around £5. I've just checked the item description and it DOES only state resolutions of 1920 x 1200 - that will teach me for not reading things thoroughly. I bought it because I just assumed DVI-D was going to work - regardless of the length.

I've now ordered another 3m one from Amazon. This is manufactured by Lindy and DOES claim to support "up to" 2560 x 1600. So, if that doesn't work I will be sending it back - I get the impression Amazon's returns system is quite painless. (This cable is about £25. There are others double the price so we shall see whether I have to resort to one of those yet.)

The repeaters were expensive and only stated supporting resolutions of up to 1920 x 1200.

Thanks for the explanation, 4wd. I'm surprised that cables are so rubbish over such small distances. I thought the "digitalness" would be more capable.

4wd

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Re: when is a cable not a cable - when it's a DVI-D
« Reply #5 on: August 19, 2011, 03:38:38 AM »
See the edit I added above - you'll probably find the cable you bought was DVI-D Single Link.

Wikipedia has a decent DVIw explanation.

I'm surprised that cables are so rubbish over such small distances. I thought the "digitalness" would be more capable.

I've been caught out many times, usually with USB cables, (some are just so crap they won't work past a meter).
« Last Edit: August 19, 2011, 03:48:05 AM by 4wd »

nudone

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Re: when is a cable not a cable - when it's a DVI-D
« Reply #6 on: August 19, 2011, 04:27:56 AM »
Well, that's the thing, I wasn't awake enough to spot the original item description only stating 1920 x 1200, but I did make sure it said dual link - this is the item's title on ebay "3M DVI-D Male to DVI-D 25 Pin Dual Link Gold Cable Lead".

I did wonder if I was missing something obvious so I did check if there was any physical difference between the the two cables and they both look identical in connection socket terms. I've just taken a (bad) photo to show that the black plug cable looks like a normal dual link - I've several single link cables which do look different (less pins, just as wikipedia mentions).

dvi-d-cables.jpg

Note the number of pins are the same, width of "flat" pin is the same (these can be different depending on spec of cable). Only difference I see is that the green socket cable (the 2m working cable) has a slightly thicker cable than the 3m black socket cable.


lotusrootstarch

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Re: when is a cable not a cable - when it's a DVI-D
« Reply #7 on: August 19, 2011, 04:32:41 AM »
How about getting an HDMI 1.4 cable with DVI adapter? Wouldn't it be a more future-proof investment than getting a "monolithic" DVI cable? just a thought.

I have a feeling that we won't be seeing a high-end gfx card with onboard DVI in a few years.
Get my apps in Android Market! Go droids go! :)


nudone

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Re: when is a cable not a cable - when it's a DVI-D
« Reply #8 on: August 19, 2011, 04:43:30 AM »
Maybe - but again, I've no confidence in these things working. To me, it seems reasonable to expect DVI-D "dual link" to work - the specification says it does, beyond higher resolutions of 2560 x 1600. I don't expect magic cables to be required to make it work. If things are so different in the high res world then they ought to make the sockets on the monitor completely different to avoid confusion with the non magical DVI-D socket (call it DVI-D triple link or something).

Future-proofind may be an issue for me later. But I expect it will be the same old nonsense. The HDMI cable will say it works - but it won't work beyond 2 meters unless it's only at 1920 x 1080.

I mean, this isn't cutting edge technology. LCD 30 inch monitors have been around for years - is it so hard to make a cable over 2 meters for them.

Anyway, we shall see. The Lindy cable I've ordered claims it will work at the res I need. I will be more surprised if it does work, rather than surprised that it doesn't.

JavaJones

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Re: when is a cable not a cable - when it's a DVI-D
« Reply #9 on: August 19, 2011, 04:39:45 PM »
It's not so hard to make such a cable but it does cost money so it's just not reasonable to expect a cheap £5 cable to do high resolution over longer distances. Monster Cable may be a complete rip-off, but they're not totally wrong in that cable quality *does* affect signal transmission length. Where the BS comes in is that it will "degrade your picture quality" with a digital signal. The reality is it either works or it doesn't, as you found. :D

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4wd

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Re: when is a cable not a cable - when it's a DVI-D
« Reply #10 on: August 20, 2011, 06:22:05 PM »
How about getting an HDMI 1.4 cable with DVI adapter? Wouldn't it be a more future-proof investment than getting a "monolithic" DVI cable? just a thought.

Considering over the last couple of years they've rolled out HDMI 1.1 -> 1.4, getting a HDMI 1.4 cable is no guarantee of longevity.

Quote
I have a feeling that we won't be seeing a high-end gfx card with onboard DVI in a few years.

Some manufacturers' have already put DisplayPortw outputs on gfx cards....as with everything: The good thing about 'standards' is that there are so many to choose from.

worstje

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Re: when is a cable not a cable - when it's a DVI-D
« Reply #11 on: August 20, 2011, 06:39:39 PM »
4wd reminded me of this particular comic:

XKCD 927: Standards



It was just begging to be posted, sorry for slightly-offtopic comment. :)

nudone

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Re: when is a cable not a cable - when it's a DVI-D
« Reply #12 on: August 24, 2011, 06:38:52 AM »
The Lindy 3 meter DVI-D cable has arrived...

...it works.

So, just for the record, if you need a 3 meter DVI-D cable that will work with a 2560 x 1600 resolution monitor - buy a quality branded cable, e.g. a Lindy. (It doesn't seem to be that you need to go crazy and buy a hundred dollar cable, just get something that's more than a few dollars - and DOES state that it supports 2560 x 1600.)

f0dder

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Re: when is a cable not a cable - when it's a DVI-D
« Reply #13 on: September 01, 2011, 10:17:27 AM »
Some manufacturers' have already put DisplayPortw outputs on gfx cards....as with everything: The good thing about 'standards' is that there are so many to choose from.
Especially when greedy bastards want license royalties... then new stuff emerges. Like in the case of HDMI -> DisplayPort.
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