Help My LCD Is Having Problems Running at 75hz on through DVI

[Eddie33081]

I recently bought a 940b samsung syncmaster. I was using analog and I wasn't getting any problems. When I finally got hold of some DVI cables. My LCD gets all messed up. It looks like I have bunch of damaged pixels. Also it doesn't let me exceed 75hz while in digital. Theres only 60hz and 75hz. I don't witness any problems if it's running at 60hz. In analog mode, I only witness problems if I go beyond 75hz. There no damaged pixels but rather my screen is cut off.

My videocard is a 6800le unlocked to the maximum pipes and shaders. I ran several tests using analog and it appeared that the pipes werent damaged. I'm running the latest nvidia detonator drivers. I was thinking it was the drivers for my videocard or maybe the drivers for my monitor. I know how to properly remove my drivers for the videocard but not for my monitor. Any help would be greatly apprieciated.

 

[us3rnotfound]

run it at 60.

 

[Viper96720]

use 60 lcd not equal to crt regarding refresh rate.

 

[xtknight]

Not understanding completely. You mean only 75 Hz in DVI mode produces damaged colors, and not 75 Hz in VGA? It's possible the pixel clock is just a couple hertz too high. It has to be rounded to 76 Hz sometimes.

 

[Eddie33081]

Yeah in DVI mode running at 75hz it produces damaged colors. In VGA, it doesnt. I play of lot fps games and I want to have the best performance possible. The main reason why I bought a syncmaster was because of amount gaming I do.

 

[killnine]

Yeah, but the way LCDs work is different than CRTs. The crystal isn't flickering like a tube in a CRT is, thus refresh rates don't mean quite the same thing. Whats most important is the response time.

Refresh rate is to CRT as Response time is to LCD.

Tell that to the IOWA test of basic skills! Anyhow, DVI will give you MUCH better color display and you don't want to waste that nice syncmaster screen with crappy picture that VGA will give you.

 

[xtknight]

Before you try a new DVI cable see if you can fix this problem using the ForceWare driver control panel (where you force AA, etc). You're using the rig in your sig I assume?

Find Screen Resolutions & Refresh Rates and go to Advanced Timing. Under "vertical lines" put in 73 Hz instead of 75. See if that'll work. If that still produces artifacts, find the highest you can go before it craps out (using the vertical edit box only). Say it starts crapping out at 74 Hz. Note what it says under horizontal in Scan rate. Then see if both are within spec of your monitor. I can help you with that if you just tell me the max horizontal and max vertical when artifacts start. Also note the Pixel clock value.

There is still a big difference between refresh rate and response time. Refresh rate measures how many times a second the electron guns scan the screen vertically. Response time measures how fast a crystal can turn from on to off. Response time can vary among the color spectrum while refresh rate does not. Additionally, response time is something on the level of pixels, not a whole repaint. The effects of a slow response time versus a slow refresh rate are very different. A slow response will produce blurring and streaking while a slow refresh rate will be flickery like a strobe light.

Happy New Years!

 

[Peter]

It's an NVidia card? Better keep DVI signal frequency as low as you can. 60 Hz is fine - LCDs don't flicker.

 

[Puffnstuff]

Nvida cards do just fine with dvi output. I'm running 3 lcd's at home through a 6600gt, 6800gt and 7800gt co and they all do just fine. An lcd running a 60hz is just fine however I run my planar at 75hz. Perhaps you did something to the video card when you flashed it. Why don't you reflash it to the original bios and see if the problem persists.

 

[gac009]

60mhz is the recommended rate for your monitor in DVI, 75 is just the max. there is nothing wrong with your drivers, monitor or video card most lcds like to be run at their native spec in DVI mode, its the trade off for getting such a nice clean picture.

run it in 60mhz and play your games, then come back if their are any problems.

 

[the cobbler]

60hz definitely best for LCDs

I have Samsung 710N-2 @12ms response. If I run it at 70hz or 72hz (both officially supported refresh rates) I get bad backlighting and the monitor actually makes an audible high-pitched whine. I can only assume that's not good, heh.

 

[Peter]

Originally posted by: Puffnstuff
Nvida cards do just fine with dvi output. I'm running 3 lcd's at home through a 6600gt, 6800gt and 7800gt co and they all do just fine. An lcd running a 60hz is just fine however I run my planar at 75hz. Perhaps you did something to the video card when you flashed it. Why don't you reflash it to the original bios and see if the problem persists.

NVidia's chips are known to produce substandard DVI signal integrity at high frequencies - which causes exactly the symptoms described by the original poster. Things get worse the closer you get to DVI's 165 MHz clock limit.

 

[0roo0roo]

go to howstuffworks.com and look at how lcds work. 1hz would be flicker free on an lcd. it just would be one very still frame per second. second of all lcds arent fast enough to take advantage of really high refresh rates anyways, the pixels change slowly, good chunks of the screen will probably never change past 30fps. 3rd, your video card is pretty slow to be worrying about having a 60fps minimum.