DVI vs analogue input

[Doom9]

Since last Friday I have a Creative GF4TI4200 card with a DVI output. I also have a Philips 170B 17" flatscreen. Now since I put this card in and connect the screen via DVI cable I can see very nasty artifacts when watching movies or playing 3d games. Basically whenever a scene is pretty dark it gets messed up.. I get big blocks that I don't see when I switch back to the analogue connection. A very good example to see this effect would be the Universal studio logo..
Just wondering.. has anybody else noticed such an effect? Is the DVI connection that much better that you can see the slightest flaws even in dark parts or is there something wrong with the DVI connection? Considering that when I have a pitch black screen in a movie it gets messed up too (looks like I have noise on the screen..) I suppose it's the latter but you never know.

[lilhobo]

have u used the new HQWL 30.82 drivers??

[Doom9]

yup. I'm back to using the regular analogue input. While the picture is better in digital mode I can't take the nasty blocks in video and games in dark areas.

[daveidmx]

i think that my video card handles overlay mixing differently when using vga vs dvi. do you only notice that noisy schtuff on overlays? if you open up a screenshot in photoshop or picture viewer or some other GDI app does it look fine?

[Scipio]

- cable damaged?
- dvi module damaged? -> RMA the card
- try another flat panel with that card/another DVI gfx card with your panel

[snw]

I have exactly the same flatscreen monitor as you connected to a gf4ti4600 trough dvi and the same problems with dark areas in movies. I just tried switching between analogue and dvi and trough analogue it looked normal but trough dvi the artifacts appeard, as yóu wrote. So I don´t think you have a bad card or cable, it´s just dvi that shows a more detailed picture and then problems you normally wouldn't see appear... Don't know about any solution, but you can always have both cables connected and switch between dvi and analogue when playing a game or watching a movie.

[Doom9]

I doubt it can be artifacts.. I tried playing Serious Sam where the graphics are computer generated and not really subject to compression artifacts.. but the problems remain.

@horestes: gfx cards with DVI output and flatpanel displays is not really something you have on the double or many of your colleagues have. In fact.. I would know of exactly none who has a DVI output or a flatpanel with DVI input.

[FrEEwilL]

how did you set res and refresh rate with dvi ?
i had red lightning edge artifacts on overlay pictures, yet no problem on desktop pictures, when i set 1280*1024@75 with my radeon and 17"TFT. but it disappeared @70 or 60.

[Scipio]

Originally posted by Doom9

@horestes: gfx cards with DVI output and flatpanel displays is not really something you have on the double or many of your colleagues have.

Hmm, then you've got less "nerdy" friends...
Although I don't have a flat panel monitor, all latest gfx cards (Radeon 8500, many GF4MX and GF4Ti cards, also some GF3s) have that... so it's not too uncommon these days if you're trying to stay up to date (but that's seems only really necessary if you're a gamer since working people don't need that 3D power).

your problem could also be related to a bad monitor DVI input module - snw has the same monitor and the same problem with DVI... but he also has the GF4Ti, so we can't come to a conclusion, yet - I don't know, but I think the Ti has an on-chip DVI encoder.

[omol]

Originally posted by Doom9
Since last Friday I have a Creative GF4TI4200 card with a DVI output. I also have a Philips 170B 17" flatscreen. Now since I put this card in and connect the screen via DVI cable I can see very nasty artifacts when watching movies or playing 3d games. Basically whenever a scene is pretty dark it gets messed up.. I get big blocks that I don't see when I switch back to the analogue connection. A very good example to see this effect would be the Universal studio logo..
Just wondering.. has anybody else noticed such an effect? Is the DVI connection that much better that you can see the slightest flaws even in dark parts or is there something wrong with the DVI connection? Considering that when I have a pitch black screen in a movie it gets messed up too (looks like I have noise on the screen..) I suppose it's the latter but you never know.

Same flat panel and same GPU but it's leadtek. No such problem here. With DVI, you can switch resolution. Switching resolution in analog with flat panel is messy. In your case, it seems the DVI cable or the module is faulty.

regards,
omol

[fisix]

i had a geforce ti4600 hooked up dvi -> GEM 19in flat screen, but i don't think i saw what you are seeing. i watched lord of the rings off of dvd and didn't see any wierd blocking.

do they look like the blocks you get when divx or mpeg2 don't have enough bitrate to go around? squares with all the same color? were yours rectangles or maybe lines?

my bet is that the cable is either damaged or it isn't seated well at one of the ends. i'm not positive, but i think if you had an intermittent ground, you might get the same garbage. the only way to know for sure is to switch out the cable, then the monitor, then finally the card. hopefully you have something nearby.. usually a cable can be returned easily, and sometimes local shops will let you test with a floor model monitor... and if it's neither of those, you are left with RMAing the card.

the card i use is one of the MSI made ones (for reference)

-fisix

[\AX]

due these black areas sort of move like stable clouds? does your monitor look like a picture developed from a exposed roll? due the spots just look like a lack of light or the pixels actually black?

sounds to me like you might have to send that card back, make sure you connections are clean, or make sure there is no funky magnetic's/field's around your setup.

just to play safe i'd send the card back, while your waiting for a new one dig up some more info/feedback, and when you get it back tackle it head on with the brand new card.

[smiller667]

I am just guessing here as I don't have any hands-on experience with DVI & flatscreens ... it sounds like your setup somehow suffers from too little colour depth - no idea what might actually cause this particularly on your DVI-out (or DVI-in of your TFT), but I seem to recall that early TFTs did indeed have a limited colour depth ... and no, I don't have any links to prove this idea.

[dar1us]

there is no special settings you must use to make it work properly, like in nView or what ever it is, also - are you using any GeForce tweaking programs?

[Cryect]

I have a Radeon 8500 LE that I'm using with DVI with my LCD (Samsung 171P) and don't have any problems at all.

[iceknight]

Tomshardware did a review a few months ago on the Philips 170B2M (close to the 170B, just newer) and the article mentions bad response times and a "wake" when playing games. Philips website does mention that you should have your video card set to 1280x1024 and be running a driver that they have (redundant info probably). Only other thought I have is try a different DVI cable.

[Doom9]

DVI cables are pretty darned expensive, especially if you have no further use for them after a test ;) I'll be getting another TFT screen though (equipping my secondary PC with a TFT screen as well) so I should be able to verify if it's a problem with the screen soon enough (the 2 weeks waiting time they told me about is almost up).

Of course I'm using the screen's native resolution, and in normal scenarios (office apps, bright parts of a movie) the quality of the DVI connection is nothing short of stunning and better than anything I've seen before... so it can't be that broken. And no, I don't use any tweak programs, not even nview.

[maven]

just for the record:
i use an asus gf4 4400 w/ DVI on a compaq tft 8030 and everything is fine (so it's probably not the geforce but rather the display?)...

[Absimilliard]

I remember this could be a problem with AMD and VIA Chipsets in conjunction with high AGP-Settings (4x and Fastwrite enabled).

Propably the latest 4in1 will resolve this. But I think a firmware-update of the card is needed.

Do you use the reference Detonator of NVidia?

[ArsCraven]

Wow, what a bunch of wild stabs in the dark.
It's doubtful that you have cable problems. It's not a scaling issue if you're at your display's native resolution. If the artifacts look like the ghost of a previous image then the issue is related to the response time of the pixel elements. Lower your refresh rate. Since this is not a CRT, you wont see flicker low refresh rates. No LCD has a response time to match a 60+Hz refresh anyway; unless there's one with an <15ms response that I don't know about.

If the artifacts haven't gone away, let's verify a few things first:
Take a screenshot of the artifacts. Can you see artifacting in the screenshot on your LCD? Can you see artifacting in the screen shot on your CRT?

If you can see the artifacts in the screenshot, but only on your LCD, then your display isn't adjusted properly. All video codecs hide quantization assuming that the response curves of the display are at sane values. Normally the patches of not-quite-black and black that I assume you're seeing would be down in the 'toe' of your display's luma response curve; making it impossible to discerne between them. Try lower the brightness, or lowering the contrast. To test this hypothesis, try messing with the settings on your CRT to see if you can make the artifacts appear there.

If you can see the artifacts in the screenshot and on both your CRT & LCD, then please post them here. If you can't see the artifacts in the screenshot on any display then I need more data, maybe a picture of yer screen from a really good digital camera?

[fisix]

i guess the only reason why it seems unlikely that comparing the image on a crt to the image on his dvi linked lcd will help is because he doesn't see any of the block issues when he connects the lcd with a simple svga cable.

if i knew more about the pinouts on the cable, then i could rule out the cable or the solder joints the connectors make at each end.

i'd like to think that we could rule out software problems because doom9 is contientious enough to have installed latest drivers and searched for similar problems with fixes. AND since i just recently installed the same or similar parts and they worked fine with the most recent drivers, there doesn't seem to be any obvious issues there.

it could be that there was a specific .inf file for his lcd that has an error that limits the color depth in dvi mode, but i doubt it. one way to test it would be to delete the .inf and rely on just the 'standard' screen discriptor (what i used).

anyway, if it's not software, that leaves either the connections, or either of the ddcs (digital to digital converters) in the screen or the card. i guess either ddc could have a cold solder joint just as easily as the cable or the connections could, but it just seems more likely that the cable or the connectors (parts that are man-handled) are the culprit.

i remember that connecting the dvi cable was a bitch at the lcd side.

anyway, for these reasons, i still vote on the cable first, then the lcd, then the card.

so whats the solution, doom9?

-fisix

[Timaestro]

I have the same monitor (170B)/same video (GF4 4600) and same problem ... I believe its not a video card/cable problem. From my experience if you use power strip to calibrate the monitor contrast and gamma brighter the artefact will disappear as matter of fact I noticed the artefacts only appear when really dark. This takes a long time fine tuning. Pwer strip only apply setting for most games(16bit+) and most windows appz, apparently power strip don’t work on video overlay (I noticed there is an option in nvidia's 30.82 driver to adj overlay setting but its disable or is it disabled because I'm using nView?) DVI is problematic at first but the quality is so much better in still images so it’s worth it.


My first post, I waited five days to post my discovery hope it's helpful.:p

[Doom9]

we can rule out the card. I finally got my new display today (Samsung Synchmaster 191T, a 19" baby and a good one :). It comes with both analogue and DVI cable and I connected it using the DVI now and there are no artifacts anywhere to be seen (just finished watching the first movie).

@update: I switched to the old DVI cable and got no artifacts either so the problem is the old monitor.. either the settings or the DVI input are screwed. When I have time I'll mess around some more.

[Doom9]

It's doubtful that you have cable problems. It's not a scaling issue if you're at your display's native resolution. If the artifacts look like the ghost of a previous image then the issue is related to the response time of the pixel elements. Lower your refresh rate. Since this is not a CRT, you wont see flicker low refresh rates. No LCD has a response time to match a 60+Hz refresh anyway; unless there's one with an <15ms response that I don't know about.
that's definitely not it.. messing with the refresh rate was the first thing I tried and by default the display uses 60 Hz so that's what I've always used. And the reaction time of that particular panel is 40ms.

[fisix]

thanks for the updates. looks like the problem is the monitor itself or its connector.

can you return the monitor?