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A DVI desktop problem


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#1 ministeve

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Posted 27 July 2004 - 07:07 AM

I know this is a mobile nvidia forum, but I know you're excellent at modding infs.
So here's my question.

I purchased a FX5200-based Albatron AGP card for my desktop and a DVI 1280x1024 Iiyama LCD monitor.
  • boot or splash screen
    Both in Win 2000 splash screen and the Mandrake LInux boot screen, I noticed strange flickering segments of green pixels at the leading edges of characters. For example, if the char is say white on black on the Linux boot screen, the transition on screen between black to white is not crisp, there's a green pixel where the "black" should turn to "white". Some chars are affected some aren't, but, as the boot screen scrolls up, any affected char keeps the "defect" while moving up.
  • High res screens
    The window hi-res screen is fine at 1280x1024 60Hz. This is the max resolution that is allowed by the installed 5x.xx driver.
    The Linux hi-res screen 1280x1024 75Hz is not entirely good. There are isolated fixed red pixels always in the same place and
    sometimes vertically aligned, not contiguous red pixels.
I tried changing the cable and things got much worse (tried two other cables). Pulsating horizontal red lines all over the screen in Linux. Boot screen much worse (many more chars with green leading edges).

Now I'd like to test what happens with the Win nvidia drivers at 75Hz. But the driver doesn't let me do this. Can I somehow use a modded inf to get that resolution? Could newer 6x.xx help?

#2 Teraphy

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Posted 28 July 2004 - 10:39 AM

I most likely have a bad case of "dontknow-itous" in Linux (no offense dontknow) :)

Could there be bad timing for the display which results in pulsating?

I get a flash of a green screen upon Windows bootup. This I deemed a normal "feature"

Do you ever get the normal color pixels back?

DVI's are nice and should be able to do 75Hz. The NV_Modes line should help that but must include your device id. In the 6x.xx line is also the custom resolution panel which you can add any type of resolution desired.

#3 mobilenvidia

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Posted 28 July 2004 - 12:48 PM

Are the pixels always in the same place ?
If so then you may have dead pixels, usualy when you notice them all 3 colours have died and you get a while dot always on or on a white screen a black dot always off.

LCD pixels are made up of 3 colour subpixels, the combine to make all the colours.
When on of the colours dies then what you experience might be happening.

There is a monitor tester it's webbased (ie no download), I mentioned it here somewhere (as it was useful), but I have no idea what I did with it. (link)
Run this first to test the screen.

Other than that my advice runs out,


Pieter.

#4 ministeve

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Posted 31 July 2004 - 05:55 AM

Thanks a lot for answering.

I most likely have a bad case of "dontknow-itous" in Linux (no offense dontknow) :)

:)

Could there be bad timing for the display which results in pulsating?

Could be, but linux timings nowadays are standard vesa. More over that would not explain why it is almost perfect with one cable and terrible with others.

I get a flash of a green screen upon Windows bootup.  This I deemed a normal "feature"

No, my flashes are flashes of groups of lines. The occur when the hi-res driver is already on, not at bootup.

Do you ever get the normal color pixels back?

They're switching from one fixed color to the right color very quickly, and with the "almost good" cable tend to stabilize.

DVI's are nice and should be able to do 75Hz.  The NV_Modes line should help that but must include your device id.  In the 6x.xx line is also the custom resolution panel which you can add any type of resolution desired.

Yes, DVI is perfect for using a DFP and an inexpensive old CRT on the VGA output. However reading the nv linux forums, i see that many people are having troubles especially with cards featuring a second DVI output. Not my case, but may indicate that implementations are not mature -_- .

As for the resolution panel, I hoped it could work. I tried setting 75 Hertz in a 61.77 and it accepted the timing, but the monitor stills says it is still receving a 60 Hertz signal. Is this panel fully functional?

Since I can't set 75 Hz in Windows and the problem occurs only at 75 Hz, I can't be sure at the moment it's not Linux-dependent.

#5 ministeve

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Posted 31 July 2004 - 05:59 AM

Are the pixels always in the same place ?
If so then you may have dead pixels, usualy when you notice them all 3 colours have died and you get a while dot always on or on a white screen a black dot always off.

LCD pixels are made up of 3 colour subpixels, the combine to make all the colours.
When on of the colours dies then what you experience might be happening.

There is a monitor tester it's webbased (ie no download), I mentioned it here somewhere (as it was useful), but I have no idea what I did with it. (link)
Run this first to test the screen.

Other than that my advice runs out,


Pieter.

I tested the monitor with the tester in the monitor cd, it's ok.
The pixels occur at the same place in the picture, that is, for example, they are tied to a position in particular terminal window, or to a char in the boot screen. If I move the window, the pixel moves with it. I don't think it's a physical pixel problem.

#6 Teraphy

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Posted 31 July 2004 - 09:30 AM

Now the question is how it handles with other monitors? I can't imagine the driver singling out a pixel. If it was purely the cable it also wouldn't be picking on certain pixels. Is it a TFT LCD? I think most LCDs are these days.

#7 ministeve

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Posted 01 August 2004 - 05:40 AM

Now the question is how it handles with other monitors? 

Right, this is the question, but I cannot find easily other DVI DFPs capable of 75Hz to try.

is how it handles with other monitors?

I agree, I think I should see the same artifacts with the windows driver at 75 Hz if only I could make it work

If it was purely the cable it also wouldn't be picking on certain pixels. 

Hmm...This is reasonable, but I wonder if certain screen images could cause "stable" artifacts, that is, ones that are tied to the image, like some of the ones I see. There's a red pixel on the menu bar of an ETerm---a Linux terminal window---which keeps its position in the ETerm when I move it. This artifact tends to disappear with time, and is totally absent at 60Hz. Other artifacts are truly random. It's a strange situation indeed.

Is it a TFT LCD? I think most LCDs are these days.

Yes.

I'll see if I can mod the inf to get 75Hz working and report back if and when I succeed.

#8 ministeve

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Posted 12 August 2004 - 09:56 AM

No, the card will not go 75Hz DVI under Win. Moreover I tried monitor/cables with an Apple laptop and the picture is perfect. Looks like the card is out of shape.

#9 Guest_greg_*

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Posted 15 February 2006 - 12:54 AM

No, the card will not go 75Hz DVI under Win. Moreover I tried monitor/cables with an Apple laptop and the picture is perfect. Looks like the card is out of shape.


Is there anyone still left to read this? :)

I found that if you set the AGP speed on the BIOS from 8x to 4x it helps quite a bit. Also, the green pixel problem is affected by the monitor you use. With a 17" Philips 170B2 it was pretty bad, but with a 19" Samsung 930B it was hardly noticable, even before setting AGP4X.

#10 Ice-Tea

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Posted 08 March 2006 - 05:16 AM

Also, the green pixel problem is affected by the monitor you use. With a 17" Philips 170B2 it was pretty bad, but with a 19" Samsung 930B it was hardly noticable, even before setting AGP4X.


Early DVI implementations suffered from poor performance at high speeds. The new receiver chips feature equalisers, hence the difference.