changing xserver refresh rate

[naughtysriram]

i installed fc7 successfully on my desk top.i hav a 17" samsung syncmaster tft display.
when it gets booted, on the gui mode (once when xserver is started automatically), i can see the login manager but it is quite distorted..! once i enter my session i can rectify that by changing the refresh rate (from 60 to 75 Hz in my case) either from KDE or GNOME. all i need is to change the refresh rate at boot time( before xserver is started) so that my login manager appears good to my eyes...any body who comes up with a way or n idea plz write.
thanks in advance.

[RJFUatHOME]

Try editing your xorg.conf file to run at 75Hz.

See this post with instructions on using gtf to output a mode line for your conf file.

http://fedoraforum.org/forum/showpos...99&postcount=6

[naughtysriram]

thanks....got the idea and i tried it...its working fine now...by the way i configured my monitor too,,,..thanks a lot.

[pobbz]

This is a bit OT, but what purpose exactly does the concept of 'refresh rate' have in the context of tft monitors? I know tfts have a response time of some milliseconds, but that isn't the same thing as the refresh rate of a crt monitor.

So if you say you have a tft operating at 75MHz, what does that mean exactly?

EDIT: 75Hz, obviously...

[naughtysriram]

as far as i now...each resolution(eg. 1024x768) has a basic refresh rate..when the OS works on this its fine...you can also change(tats wat i did) the refresh rate to get desired results...like..some movie players might need special refresh rates configured for good picture viewing...

The refresh rate (or "vertical refresh rate", "vertical scan rate" for CRTs) is the number of times in a second that a display is illuminated. This is distinct from the measure of frame rate in that the refresh rate includes the repeated illumination of identical frames, while frame rate measures how often a display can change from one image to another.

For example, a movie projector advances from one frame to the next 24 times each second. But each frame is illuminated twice or three times before the next frame is projected. As a result, the movie projector runs at 24 frames per second, but has a 48 or 72 Hz refresh rate.

Increasing the refresh rate decreases flickering, reducing eye strain. However, if you specify a refresh rate beyond what is recommended for your monitor, you might damage it [1] and cause it to start popping.

For computer spreadsheets, the term could also be applied to how frequently a cell is updated with a new external value from another source (for example; a shared public spreadsheet or other external data feed).

try wikipedia/google for more precise details.

[pobbz]

Yes, nughtysriram, I understand all that. What I was wondering is that if you e.g. configure xserver for a certain refresh rate, say 75Hz, what does it do when a tft is attached? How does it differ from 60Hz, for instance?

I don't own a tft or lcd monitor myself, so I can't try this out. However, knowing how a tft monitor works, it sounds a bit strange to talk about refresh rate as it clearly is a concept that is defined in terms of crt monitor's workings.

[RJFUatHOME]

LCDs use different refresh rates just like CRTs do. To be honest though, you don't see the noticeable flickering at lower refresh rates on LCDs like you do on CRTs, at least on mine anyway.