can't set 60hz v refresh rate

[Stuart Sears]

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sean enlightened us with the following gems on 15/10/05 18:34:
> David Becker wrote:
> 
>> sean wrote:
>>
>>> On fc4, updated, I have a dell flat screen with a intel i915g chips -
>>> using xoreg i820 - that I want to run at 1280x1024x60.
>>>
>>> Desktop-> Preferences -> Screen Resoltuion does not let me change the
>>> refresh rate. It stays at 75hz.
>>>
>>> I hand edited xorg.conf so that the monitor section has
>>>
>>> VertRefresh   60
>>
>>
>>
>> It's best to leave these values at whatever your monitor specifies.
>>
>> If X doesn't automatically choose a suitable modeline for your monitor
>> (I assume you have some kind of TFT that doesn't work above 60 hz), then
>> you can calculate these values yourself;
>>
>> Find a modeline calculator on the net. Given your monitor's
>> characteristics, they allow you to fix one or more parameters (such as
>> Vertical refresh rate and resolution) while finding the modeline values
>> to accommodate.
>>
>> Copy the result of the modeline calculator to the 'Monitor' section of
>> xorg.conf.
>>
>> I for instance used this to calculate a suitable interlaced
>> (exaggerated) 200Hz frequency for PAL television viewing as in:
>>
>> Section "Monitor"
>>         Identifier   "LG915FTPlus"
>>         VendorName   "LG"
>>         ModelName    "915FTPlus"
>>         HorizSync    30.0 - 107.0
>>         VertRefresh  50.0 - 200.0
>>         Option      "dpms"
>> # TV (PAL) Viewing
>> # Measured xawtv dimensions at 760x573
>> # 200hz
>>         Modeline "760x573 at 200i" 64.46 760 792 1032 1064 573 582 593 603
>> interlace
>> EndSection
>>
>> Then insert or append the modeline identifier ("760x573 at 200i") to the
>> list of Modes in the 'Screen' section of xorg.conf.
>>
>> Regards,
>>
>>     David
>>
>>
> 
> 
> Great idea. I'll try it.
> 
> sean
> 
there is a built-in Modeline calculator on your system, called gtf
syntax (for 1024x768@ 60Hz):
gtf 1024 768 60
should generate output a bit like
# 1024x768 @ 60.00 Hz (GTF) hsync: 47.70 kHz; pclk: 64.11 MHz
  Modeline "1024x768_60.00"  64.11  1024 1080 1184 1344  768 769 772 795
 -HSync +Vsync
you can drop the -HSync +Vsync bit, and this would give you a modeline
(in your Monitor section of xorg.conf)...
Modeline "1024x768" 64.11  1024 1080 1184 1344  768 769 772 795

I used to have to do this for my Dell widescreen laptop.

Regards

Stuart
- --
Stuart Sears RHCE RHCX
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