Cannot get 75hz on TFT monitor

[Erik Ahlner]

Matthias Hopf wrote:

>On Oct 31, 05 15:44:03 +0100, Erik Ahlner wrote:
>  
>
>>Michel Dänzer wrote:
>>    
>>
>>>>So, there's something jiffy about DVI.. it works in 75hz in windows, but 
>>>>in Xorg, it just gives me 60.
>>>>        
>>>>
>>>The panel probably runs at 60 Hz anyway, so that should be ideal.
>>>
>>>      
>>>
>>No, it does *not* run at 60hz. There's a VERY noticable difference 
>>    
>>
>
>Yes, it (presumably) does.
>The effect you're seeing is from not having a sync-to-vblank on the
>computer framebuffer side, but only on the panel internal framebuffer.
>
>If you run your VGA at 60Hz the panel can either directly use the input
>signal, or sample into its internal framebuffer which is then scanned
>out. In both cases you see the data exactly as released by the graphics
>card, which includes tearing due to missing sync-to-vblank.
>
>If the VGA runs at 75Hz, the data is always sampled into the internal
>framebuffer of the panel, which is typically double buffered and is
>synced to vblank (of the internal 60Hz sampling).
>If the panel wouldn't have a double buffer, you would see tearing in
>this case as well.
>
>Personally, I dislike having the panel run at a different frequency due
>to studdering effects, but for Quake 1 you should be pretty close to
>77Hz, right.
>
>There are few panels that can scan out at different frequencies than
>60Hz, and even fewer at higher frequencies.  My projector is optimized for
>video, and thus can scan out at 47.952, 48, 50, 59.94 and 60 Hz, but
>not at 75Hz.
>
>Matthias
>
>  
>
Thanks for the explanation. Either way, now that i have fixed the issue 
with a nvidia specific line in xorg.conf (see my other post about this), 
all is fine. I can finally play quake (almost) the way it was meant to 
be played; at 75hz :)

Regards,
Erik Ahlner