Weird image with VGA->DVI adaptor

[Vercas]

I have a VGA-mother to DVI-father adaptor for my main display (I have two) and I have just noticed strange behavior: noise. The image is like getting random, weak noise all the time! It happens to the second display too. I have tried two other adapters and I have the same problem with both!

Is this thing normal?

 

[Dr Super Good]

Yes as VGA is analogue and as such it will always have noise. The adapter purly changes the analoge VGA to analoge DVI meaning that even the DVI cable will add noise to your image as well. Throw in a long cable and cheap connectors (or a lot of interfearence) and you will have noticable noise.

The only solution is to make sure your display supports digital DVI (I am sure all modern ones do) and get a graphic card with a DVI output (all modern graphic cards as far as I know have atleast 1 if not 2 or more). Then use a DVI cable to connect your graphic card directly to your display (no converters).

It should now run in digital mode. As it is transfering data, noise will not alter the image at all unless it exceedes the tolerable threshold and causes bit flips to occur on the transmitted signals (only a problem with very long cables or in noise environments like on very high mountains). This is why digital signals generally are perferable, they might have other forms of data loss (aliasing) but those are less cognible than noise. In the case of comptuers it will always be better as computers produce digital outputs anyway (has to be converted to analogue so sending as digital has no data loss at all).

 

[Vercas]

The monitors' original cables are VGA. My adapters are 4 centimeters (1.5 inches or so) long...

My main monitor has a VGA-mother on it so will the noise be reduce to a non-observable level (or disappear) if I buy and use a VGA-mother -> DVI-father cable?

 

[Dr Super Good]

No, as VGA only supports analogue transmission. You will need to use DVI all the way with a digital supporting display (accepts digital DVI) and a DVI supporting graphic card inorder to run in digital mode.

Yes using better shielded cables and connections will reduce noise but noise will always be present unless you use a direct DVI to DVI connection. If you must use VGA cause your display does not support DVi then conenct a VGA cable to your graphic card directly.

 

[BlargHonk]

If you must use VGA cause your display does not support DVi then conenct a VGA cable to your graphic card directly.

Unless he doesn't have a VGA port on his card, like most high-end GPU's currently.


Anyways, basically the only solution is different cables, or you could try cleaning the pins, doubt it's that though.

 

[Dr Super Good]

I use a DVI-VGA cable to run a old display and noise is not particually noticable. Eithor you are running a really high resolution (like 1080p or greater resolution) or are using low quality adapters (not properly shielded, poor contacts etc).

 

[BlargHonk]

I use a DVI-VGA cable to run a old display and noise is not particually noticable. Eithor you are running a really high resolution (like 1080p or greater resolution) or are using low quality adapters (not properly shielded, poor contacts etc).

... Which has the same solutions I suggested above.

 

[Vercas]

Well, my main display is 1366x768 and my secondary display is 1280x1024. The noise effect is noticeable on not-so-dark and *almost* the same color places.
Oh and the adapter is very cheap... I paid like 30 cents for it and it was the only adapter I found. It had only good reviews.
One problem might be that BOTH of my displays run on 75 hertz, while DVI is strictly limited to 60 hertz.
My video card has one VGA output, one DVI output and one HDMI output. I can't get a HDMI cable BTW...

Ok so after some long hours of filming and editing, I've noticed a pattern in the noise: lines of about 0.7 centimeters length rotating 36 (precisely) degrees to the right every second.
It seems that my problem knows some genetics too!

 

[Dr Super Good]

Try separating the cable from other cables, it could be magnetic interfearence from other cables (especially power cables).

 

[Vercas]

That might be a problem, I can't! I have like 50 cables in the back of my desk. I have 2 desktops and two laptops here with mobile phones and landlines and even the TV cable and the power cables for the fridges (one is in the building's laundry room (which is only ours, btw)) go trough there.
All the wires go trough my room.

A friend suggested me a way to fix this... I'm going to try his idea: open the adapter and fill it with some isolating gel.

 

[BlargHonk]

That might be a problem, I can't! I have like 50 cables in the back of my desk. I have 2 desktops and two laptops here with mobile phones and landlines and even the TV cable and the power cables for the fridges (one is in the building's laundry room (which is only ours, btw)) go trough there.
All the wires go trough my room.

A friend suggested me a way to fix this... I'm going to try his idea: open the adapter and fill it with some isolating gel.

Build a Faraday cage around the wire, that would isolate it pretty well.

 

[Vercas]

The gel did reduce the noise to a not-so-noticeable level! The pattern is also gone.
Some metal pieces must still be in contact in the adapter or in my video card!

 

[Dr Super Good]

Video cards are prety well designed nowdays to not generate visual noise. Even a budget 8800 GT which overheats when running SC2 does not generate much detectible noise through its DVI output when in analogue mode.

 

[Vercas]

I know but it's not the design I have my doubts about. It's the manufacturing process.
I've put gel in all the adapters and they all work nicer!

 

[Dr Super Good]

You get what you pay for. The ones nvidia provides with some of their cards seem prety good but I seriously doubt a 30 cent one is at all high quality. Yes you do not need one gold plated and crap but you do need one which has good quality joins and metal compositions as well as proper isolation.

The paterns you were seeing were probably leackage current from the mains (50/60 Hz) cause by bad quality isolation from the ground (which absorbs the radiation from nearby power cables). By isolating it, you must have improved the capacitience between the cable shielding and the transmission wire and as such less current leaks through.

Ultimatly the only way to get rid of it 100% would be to switch to digital signals which are designed to be more tolerent to noise (within reason as there are thresholds).

Build a Faraday cage around the wire, that would isolate it pretty well.

I am not too sure about that... I know it prevents electromagnetic radiation (only of a certain frequency spectrum based on the mesh density) but I do not think it stops magnetic radiation that well (caused by electron flow). Yes the two are closly related but they act differently.

Unfortunatly I have had to skip learning about them in any detail inorder to study computer science.

 

[BlargHonk]

I am not too sure about that... I know it prevents electromagnetic radiation (only of a certain frequency spectrum based on the mesh density) but I do not think it stops magnetic radiation that well (caused by electron flow). Yes the two are closly related but they act differently.

Unfortunatly I have had to skip learning about them in any detail inorder to study computer science.

They don't stop things like the earths magnetic field, but it will stop most.

 

[Vercas]

On my country's best electronics website, I have found two VGA-mother -> DVI-father adapter models. The first one and the cheapest has got a 5/5 rating with 100 or so reviews. The second one, at 2 dollars and a half, which looked more solid and all that got only 3/5 but with 50 ratings.
I've read some of them, but I couldn't ALWAYS keep in mind that 95% of the displays in Romania are CRT, 1024x768 at 60 Hz, which fits DVI like a glove! Mine are both LCD, 1366x768 and 1280x1024 and both are running at 75 Hz. DVI runs at 60 Hz ONLY so that might explain the bloody pattern.
And one more final thing. I've read, before buying my PC, that the video card has 1 VGA, 1 HDMI and 1 DVI port and I've looked at the monitors (on the same vendor's site) and NONE had any damn DVI (or HDMI) cable/port.

 

[Dr Super Good]

DVI supports up to 120 FPS, in digital mode atleast.... How else do you think NVIDIA does its full colour 3D. I am also running a 1280*1024 75 Hz LCD display via analogue (DVI->VGA) from a DVI output at 75 Hz so I have no idea what gave you the idea they are limited to only 60 Hz.

VGA fits CRT like a glove as the alalogue transmission can be displayed with minimal processing (as CRT are analogue). LCD fits DVI like a glove as again it needs minimal processing (as they are digital).

Almost all HD (not just 1080p but lower resolution HD as well) displays come with DVI or HDMI support.

 

[Vercas]

DVI supports up to 120 FPS, in digital mode atleast.... How else do you think NVIDIA does its full colour 3D. I am also running a 1280*1024 75 Hz LCD display via analogue (DVI->VGA) from a DVI output at 75 Hz so I have no idea what gave you the idea they are limited to only 60 Hz.

VGA fits CRT like a glove as the alalogue transmission can be displayed with minimal processing (as CRT are analogue). LCD fits DVI like a glove as again it needs minimal processing (as they are digital).

Almost all HD (not just 1080p but lower resolution HD as well) displays come with DVI or HDMI support.

Mine did not. It's 720p HD AFAIK. My 2560 by 1600 pixels LCD TV came with only a VGA mother port and a VGA-father -> VGA-father cable, just like my newest monitor did..

 

[Dr Super Good]

My 2560 by 1600 pixels LCD TV

Your WTF???? That is some serious TV... How much did it cost you? Just send the digital DVI down one of the umpteen HDMI ports it must have.

It's 720p HD AFAIK

Ok... Enough of me being stupid. You are probably groosly overestimating its resolution. Otherwise you have a TV worth like 3000£+.

720p is the shorthand name for a category of HDTV video modes having a resolution of 1280×720

 

[Vercas]

Your WTF???? That is some serious TV... How much did it cost you? Just send the digital DVI down one of the umpteen HDMI ports it must have.


Ok... Enough of me being stupid. You are probably groosly overestimating its resolution. Otherwise you have a TV worth like 3000£+.

The TV had a discount because of my internet, landline, TV and Digital TV packages. We are UPC's clients since it was founded (they really have the best services). It cost about 500 dollars with the discount, which was huge BTW. I think 85% or so. UPC and Sony are in some serious contracts now... They are working in selling their internet TV's in this network. (Yes, the TV has internet too, but only from digital signal, and it costs a lot, and yes, I have some apps on it like Skype and several porn networks)

So if 720p is 1280 by 720 and my main display (not the TV lawl) is 1366 by 768, shouldn't THAT mean it's 720p?

 

[Dr Super Good]

The fact remains that such a TV should have atleast 1 HDMI input as otherwise there is no practicle way to utalize that insane resolution.

Programs are being broadcast in 1080p atmost, nowhere near the insane resolution you say it has. Thus the only use of that resolution you would see is it as a computer display which means it should have some form of high end digital connection like DVI or HDMI.

 

[Vercas]

The fact remains that such a TV should have atleast 1 HDMI input as otherwise there is no practicle way to utalize that insane resolution.

Programs are being broadcast in 1080p atmost, nowhere near the insane resolution you say it has. Thus the only use of that resolution you would see is it as a computer display which means it should have some form of high end digital connection like DVI or HDMI.

If it has one, I couldn't find the protective cover over it. And VGA can only send 1280x768 signal to it (with 60 Hz). The thing is, the only HDMI computer in my house is my PC, which is like 5 meters away from the TV and it would be impractical to bring them any closer.
I have settings for the signal resolution, and it can run only at 34 Hz when at max resolution, that's why I keep it at 1360x768 (almost like my PC's monitor) for 60 Hz.

 

[Dr Super Good]

You can buy DVI to HDMI addapters which still broadcast digital signals. HDMI is digital only and as such can be mapped from digital DVI almost 1:1.

You should aim for 1960*1080 at 60 Hz, that is true HD format and what all 1080p complient displays can do.

 

[Vercas]

You can buy DVI to HDMI addapters which still broadcast digital signals. HDMI is digital only and as such can be mapped from digital DVI almost 1:1.

You should aim for 1960*1080 at 60 Hz, that is true HD format and what all 1080p complient displays can do.

1920x1080 at 59 Hz but analog signal bugs like hell every minute. Digital looks OK but it's 720p not 1080p so I use 720p.
Sorry for the cranky writing but i am on a phone.

 

[Vercas]

Updated my video drivers, the noise is back again, even stronger.

 

[Dr Super Good]

You have 4 solutions.
1. Lower the bandwidth requirements (lower refresh rate / lower resolution) so that the signal is less prone to noise.
2. Rewire your cabling so that the the display cables are subject to less noise.
3. Buy expensive cables which have better noise shielding so the signl is less exposed to noise.
4. Switch your entire system to digital only output. This will grant huge noise resilience but will not work well at all if the noise exceedes the tollerence levels of the tranmission standard.

 

[Vercas]

How can I have digital only output?
Anyway I am buying a MUCH MORE EXPENSIVE VGA-father -> DVI-father cable.

 

[Dr Super Good]

By using a DVI or HDMI output to transmit to a DVI or HDMI input. This will run in digital mode as both formats are digital and transmit images in prety simlar ways.

 

[Vercas]

Nothing in my house has a DVI or HDMI input.

 

[BlargHonk]

Best long term solution: Get a new monitor.

 

[Vercas]

In this country's current financial situation, NO...

 

[BlargHonk]

Romania... ah...

Not as bad as Greece, but still

 

[Vercas]

Not YET. Anyway, now, suddenly, the noise is gone... >.>

 

[Dr Super Good]

It can be induced by anything from illegal high powered devices nearby (violating high powered design specifications for input current) to increased solar activity (more radiation hitting surface of earth).

Even some form of high powered transmission illegally (through restricted frequencies) can cause noise.

 

[Vercas]

It can be induced by anything from illegal high powered devices nearby (violating high powered design specifications for input current) to increased solar activity (more radiation hitting surface of earth).

Even some form of high powered transmission illegally (through restricted frequencies) can cause noise.

Are you saying that I have illegal transmitters or devices of high power consumption in my house? I'd love to have an ion cannon or one of those giant satellite dishes like NASA has but I don't so it's not that.
The recently increased solar activity might be the reason... (Saw it on TV)
Or the fact that I have like 20 devices plugged in the same outlet? It's not my fault, this flat doesn't have enough outlets, and, most importantly, not close to each other.

 

[Dr Super Good]

Need not be in your home, or even street. High power consuption electronic devices like water pumps, blocks of flats (not individual flats), factory equipment all need to comply to regulations created by power utility companies. If they do not follow these (you said it yourself, your country is not the wealthiest), it can cause problems within the power network causing the AC wave to become distorted or ground potentials to fluctuate causing voltage spikes.

The fact you said it stopped though is strange even for that explination. Perhapes your flat has a floating earth / ground that was fixed? Well who cares as long as it is better.

 

[Vercas]

Yeah. Why did it return when I updated the driver, anyway? It must be a different power plan. Anyway, our country mustn't be wealthy, I meant that the population is starving to death because of huge taxes and bills and reduced low salaries. (Yes, they were very low and now they have been cut by 25%) Anyways, our electricity provider is very good and can handle much more than it currently does. They even sell 30% of the electricity. We have one nuclear power plant that powers half of the country.