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"noisy" analog signal on HD3850 AGP through DVI-VGA adapter?

Last response: in Graphics & Displays
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January 12, 2012 7:05:18 PM

I have an HIS AGP HD3850 and am trying to set up my dual display using my much beloved Samsung Synchmaster 170MP analog LCD flatscreen via DVI-VGA adapter. However, though I am getting a signal, it is a VERY noisy picture and my otherwise easy-on-the-eyes monitor is practically impossible to look at through the vibrating horizontal lines and herring-bone patterned static-like jitter that is present through this method. The digital flatscreen is perfectly steady and it is the same no matter which port is which monitor.

I have not had this issue with the analog monitor with this cord on a regular VGA out, but I don't remember for sure if I have used it previously on an adapter like this (I think I have without incident in the past.) It has the same noisy picture no matter if it solo or primary or secondary in the dual setup and I am thinking it is the card rather than the adapter as I have tried several different ones of those already.

Anybody know what could be the issue here? Could it be a driver issue, perhaps? It does it right away from the BIOS screen on...

a b C Monitor
January 12, 2012 7:48:14 PM

Check the refresh rate on the noisy monitor and make sure it is set to either 60hz or 59hz. You may be at a higher or lower refresh rate.
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January 12, 2012 8:29:20 PM

Whoa, if im not mistaken your LCD screen is over 10 years old.

It could be a few things:

It could be that your DVI - VGA adapter is not working that well, do you have a spare on hand to try that out?

Also since your LCD screen has a native VGA port and your GPU has a native DVI port - the conversion process is probably not great using your DVI - VGA adapter.

It could be that your LCD screen is almost dead, do you have another LCD screen to try out? Everything has a life span, including LCD screens.
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January 12, 2012 9:10:19 PM

Chainzsaw said:
Whoa, if im not mistaken your LCD screen is over 10 years old.

It could be a few things:

It could be that your DVI - VGA adapter is not working that well, do you have a spare on hand to try that out?

Also since your LCD screen has a native VGA port and your GPU has a native DVI port - the conversion process is probably not great using your DVI - VGA adapter.

It could be that your LCD screen is almost dead, do you have another LCD screen to try out? Everything has a life span, including LCD screens.



The LCD is trucking along nicely for its age - I actually prefer the picture on it to the digital hp lp2065 which is 4 inches larger. Samsung made that one right, I tell ya; It doesn't give me any flack on a straight vga out at all (and actually using an S-video from the tv-out on the card is not as crisp, but also less noisy - It is tolerable to look at at least though not really great.)

I'm trying some different adapters (the mac one with fewer pins seems to be a little improved and I've another with even fewer that is up next- perhaps I am getting too much information which is causing it to twitch a bit.) Also updating the drivers while I'm at it to see if there is any help there. It really seems like an interference or feedback issue of some sort soI'm wondering if some other component or fan might be causing the hooey - possibly the cold cathodes inverter?
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January 13, 2012 3:58:56 AM

OOOKAY something is definitely not kosher, but I'm not sure what it is. None of the above attempted fixes have proved fruitful. Unfortunately, there is a new problem which may have existed previously but outside of my knowledge as the speakers were not plugged in then so I would not have been aware:

So it looks like the analog video "noise" might really be some kind of actual noise issue since once plugging the speakers in, it revealed a horrific screeching sound, rather like the feedback you get when you hold a microphone too close to the speakers its connected to. And that sound actually stops when the vga monitor is not plugged into the sound card, even if the dvi-vga adapter is. Not sure what this means at all, so will post under a separate topic .
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January 26, 2014 10:32:04 AM

COLGeek said:
Check the refresh rate on the noisy monitor and make sure it is set to either 60hz or 59hz. You may be at a higher or lower refresh rate.




HAH! 10 points to you sir - Well wouldn't you know it, the refresh rate DID finally fix the issue (a year or so after I had given up on fixing it and just recently tried again) except that it was not the refresh rate on the NOISY monitor that was the problem, Changing the refresh rate on the DIGITAL monitor that was already clear improved the situation on the Analog screen! This was totally an accidental discovery because I hadn't even had the Samsung hooked up anymore when I altered it, but when doing a color calibration I just happened to see that it was set at 59hz, which I thought was kind of weird because he Analog monitor was set at 60hz and everything i've ever seen has been in multiples of 5hz, so that just didn't seem like it should be on 59 when 60 was an option, so I switched it. Then I got the bright idea to try the analog dual setup again, and bingo - no more snowy picture.

It would seem that the card was unhappy trying to do the different refresh rates of 59hz on the digital screen, while doing 60, 72, or 75 on the analog at the same time. I never would have thought to try altering the OTHER screen rate to fix the fuzzy one, but after changing it I remembered this post and thought I would try it out.

When I came across my own post while searching for a solution to a no signal problem on the same card, I figured I ought to check back in and post the result - better late than never! =) (Unfortunately, the card is dead on the no signal issue - replaced with a 4670 that is working now, which means I will have to get some kind of adapter to get the rca connections for my video out now... poop.)
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