how to make LCD works in a fixed fresh rate?

[ymwei]

Hi all,

My video card is Geforce2 MX, I bought a philips 150S3f LCD, the manual of this LCD says it is recommended that the refresh rate set to 60HZ at 1024*768 resolution.

I installed redhat 8.0, the X windows(gnome) can start up without any problem, but the only fresh rate I can get is 75HZ at 1024*768.

Can somebody give me some suggestions about how to degrade fresh rate, or point me some places where I could find useful information for this problem?

And does this high fresh rate damage my LCD?

Thanks,

Yongming

[ernestus]

Well, that's quite easy:
your XFree configuration file (in my S.u.S.E. system /etc/X11/XF86Config) must have a monitor section like that:

Section "Monitor"
Option "CalcAlgorithm" "IteratePrecisely"
Identifier "Monitor[0]" # be sure that that name also appears in the screen section
ModelName "AutoDetected"
Option "DPMS"
VendorName "AutoDetected"
VertRefresh 50-60
EndSection

Basically I deleted the Mode selector and a couple of things.

Luck!
E.

[ernestus]

In LCD low refresh rates are convenient by its own design: the ADC placed in its input works better (that's giving a sharper image) at lower refresh rates. Nevertheless, higher refresh rates are useless due LCD doesn't have the flicker problem that CRT has, and it takes a higer video memory bandwith too.

LCD monitors doesn't have any high voltage oscillator, I don't think it gets damaged by any reasonable frequencies, but who knows? ;)
(No, those frequencies won't break your LCD, it only generates a slightly blurry image :p)

E.

[ymwei]

Sorry, I am new to XFree86 configuration.

Do you mean after changing the VertRefresh upper limit blow 60HZ, I can get my monitor works at 60HZ?

I do not have modeline in my XF86config because my XFree86 is 4.x, which can be probed automaticly, can I leave other lines unchanged except degrading VertRefresh?

Thanks,

Originally posted by ernestus
Well, that's quite easy:
your XFree configuration file (in my S.u.S.E. system /etc/X11/XF86Config) must have a monitor section like that:

Section "Monitor"
Option "CalcAlgorithm" "IteratePrecisely"
Identifier "Monitor[0]" # be sure that that name also appears in the screen section
ModelName "AutoDetected"
Option "DPMS"
VendorName "AutoDetected"
VertRefresh 50-60
EndSection

Basically I deleted the Mode selector and a couple of things.

Luck!
E.

[ernestus]

Yes, that is. Xfree automatically tries the higer value you put in vrefresh.

E.