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Old 07-14-2006, 10:15 AM   #1 (permalink)
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Default refresh rates LCD

I have a Viewsonic VP171s monitor, and when I use refresh rates at 70 or higher, I get some reddish blobs between certain tones of colors.

This happens with all video cards I can throw at it, a 6800, a 5200 and my current 6200.

When used my basic 60 refresh rate, It's fine. But... My question is this. Sisoftsandra says that the refresh rate should be at least 75. Is this just for CRT's, or is my monitor just a POS?
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Old 07-14-2006, 10:52 AM   #2 (permalink)
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Hello,

When it comes to high refresh rates on LCD monitors, it's not a concern. Leave it at 60Hz if it works fine.

In fact refresh rates don't apply at all to LCD monitors because since the pixels are controlled by individual transistors, the gates of transistors are either open or closed, so individual pixels are either 'on or off' until the display changes. Unlike CRT monitors however, which use phosphors, refresh rate frequencies are a concern and higher frequencies may be needed to overcome flickering of the image - which can degrade the quality.

The reason why a refresh rate frequency settings is made available in your graphics card option is because the signal is primarily due to graphics card's support for CRT monitors and the analogue signal it uses.
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Old 07-14-2006, 11:27 AM   #3 (permalink)
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Default Re: Re:

Quote:
Originally posted by Alvin.C
Hello,

When it comes to high refresh rates on LCD monitors, it's not a concern. Leave it at 60Hz if it works fine.

In fact refresh rates don't apply at all to LCD monitors because since the pixels are controlled by individual transistors, the gates of transistors are either open or closed, so individual pixels are either 'on or off' until the display changes. Unlike CRT monitors however, which use phosphors, refresh rate frequencies are a concern and higher frequencies may be needed to overcome flickering of the image - which can degrade the quality.

The reason why a refresh rate frequency settings is made available in your graphics card option is because the signal is primarily due to graphics card's support for CRT monitors and the analogue signal it uses.
Do you get that option when using DVI?
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Old 07-14-2006, 01:01 PM   #4 (permalink)
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Do you get that option when using DVI?
Yep...

I guess there's still the question of Why does a DVI monitor operating digitally still require a refresh rate to be enforced?

The option would still be available when using an LCD monitor operating on a digital signal via DVI, because the digital monitor's display still refreshes at a specific frequency (as all displays need to know how often to refresh the display)...however the refresh rate on an LCD monitor (whether it be analogue or digital) will not affect the quality or performance of the image, unlike the flickering you might see on a CRT monitor....

...This is because the pixels of an LCD produce continuous streams of light and will only change if instructed to do so. So, if the image on an LCD display operating at 60Hz is static (for example a bitmap image), you won't see the display flicker because, although information is being sent to the monitor at 60 times a second (60Hz), the information will still be the same. Therefore, the pixels of the LCD will not change because the information has not changed...

...But compared to CRT monitors, as beams of electrons pass phosphors on a CRT monitor, it will begin to dim until refreshed because the phosphors only glow for a certain period of time, hence why you see a flickering effect of dark and bright horizontal bands.
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Old 07-14-2006, 06:38 PM   #5 (permalink)
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ah, but changing the refresh rate on my lcd DOES effect the picture. like those red blobs i was talking about, where as when i take the refresh rate down, the blobs dissapear.

this has been tested on three configs with a 6800, 5200, and a 6200. this was also the case with a different mobo-proc setup as well with the same monitor.
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Old 07-14-2006, 11:07 PM   #6 (permalink)
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LCD's have limitations and if you don't install the drivers it will be possable to set the resolution and refresh rates to ones your monitor doesn't support. So Install your monitor drivers and make sure the option to hide modes this monitor can't display is checked in the advanced tab in display properties under the monitor tab.

Your Drivers
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Old 07-15-2006, 05:40 AM   #7 (permalink)
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Originally posted by ohGrFreak
ah, but changing the refresh rate on my lcd DOES effect the picture. like those red blobs i was talking about, where as when i take the refresh rate down, the blobs dissapear.

this has been tested on three configs with a 6800, 5200, and a 6200. this was also the case with a different mobo-proc setup as well with the same monitor.
As FlashDude said.
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Old 07-15-2006, 07:14 AM   #8 (permalink)
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There's one thing I forgot to mention. If you run your monitor at non supported refresh rates and resolutions then it can damage your monitor.
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