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<A HREF="VideoModes.html"><EM>XFree86 Video Timings HOWTO</EM></A>
 <b>:</b> <EM>Questions and Answers</EM><BR>
<b>Previous:</b> <A HREF="VideoModes12.html"><EM>Using Interlaced Modes</EM></A><BR>
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  <H2><A NAME="19"></A>13. Questions and Answers<A NAME="answe"></A></H2>

<p>Q. The example you gave is not a standard screen size, can I use it? </p>
<p>A. Why not?  There is NO reason whatsoever why you have to use 640x480,
800x600, or even 1024x768.  The XFree86 servers let you configure your hardware
with a lot of freedom.  It usually takes two to three tries to come up the
right one.  The important thing to shoot for is high refresh rate with
reasonable viewing area. not high resolution at the price of eye-tearing
flicker! </p>
<p>Q. It this the only resolution given the 65Mhz dot clock and 55Khz HSF? </p>
<p>A. Absolutely not!  You are encouraged to follow the general procedure and
do some trial-and-error to come up a setting that's really to your liking.
Experimenting with this can be lots of fun.  Most settings may just give you
nasty video hash, but in practice a modern multi-sync monitor is usually not
damaged easily. Be sure though, that your monitor can support the frame
rates of your mode before using it for longer times. </p>
<p>Beware fixed-frequency monitors!  This kind of hacking around can damage
them rather quickly. Be sure you use valid refresh rates for <em>every</em>
experiment on them.</p>
<p>Q. You just mentioned two standard resolutions. In Xconfig, there are many
standard resolutions available, can you tell me whether there's any point in
tinkering with timings? </p>
<p>A. Absolutely!  Take, for example, the "standard" 640x480 listed in the
current Xconfig.  It employs 25Mhz driving frequency, frame lengths are 800
and 525 =&gt; refresh rate ~ 59.5Hz. Not too bad.  But 28Mhz is a commonly
available driving frequency from many SVGA boards.  If we use it to drive
640x480, following the procedure we discussed above, you would get frame
lengths like 812 and 505.  Now the refresh rate is raised to 68Hz, a
quite significant improvement over the standard one.   </p>
<p>Q. Can you summarize what we have discussed so far? </p>
<p>A. In a nutshell: </p>
<p>
<ol>
<li>for any fixed driving frequency, raising max resolution incurs the penalty
of lowering refresh rate and thus introducing more flicker.</li>
<li>if high resolution is desirable and your monitor supports it, try to
get a SVGA card that provides a matching dot clock or DCF. The higher,
the better!</li>
</ol>
</p>

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<A HREF="VideoModes.html"><EM>XFree86 Video Timings HOWTO</EM></A>
 <b>:</b> <EM>Questions and Answers</EM><BR>
<b>Previous:</b> <A HREF="VideoModes12.html"><EM>Using Interlaced Modes</EM></A><BR>
<b>Next:</b> <A HREF="VideoModes14.html"><EM>Fixing Problems with the Image.</EM></A>



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