Re: my dell
[Trevails with Dell's hardware support staff, snipped.]
> ... . He did also tell me that there IS one way you can fix
> it in linux, and that's by setting the clock speed slower than it's fastest
> possible speed. It would fix the problem, but there would be a slower
> refresh rate. I have no idea how to "underclock" a laptop, much less
> actually open up the case and get inside.
You don't need to deal with the hardware in order to select a lesser dotclock.
(It's not the same as CPU overclocking.)
> I don't really like the idea of
> doing that right yet though, because the thing is still under warranty and I
> don't really want to void it. Do you guys have any suggestions?
This might be able to be solved via software.
When you start up X, it normally looks at XF86Config, and uses the values in
your monitor section for horizontal sync and vertical refresh, to decide which
lines it is limited to. Then, it takes the line with the highest dotclock
that is still available.
Of course on a laptop, this can be sub-optimal - since our monitors actually
like *specific* dotclocks, to my experience a lot more than they really care
about the other two factors. This is in direct contrast to desktop monitors
which can get *really* unhappy (and can smoke, literally) if H and V are too
far out of spec... though LCDs for desktops are starting to get affordable,
and may act more like our stuff. (I wouldn't know - I have a 22" monitor for
my desk that I'm quite happy with.)
<disclaim>Your mileage may vary. If you blow up your hardware experimenting
by tweaking your H and V values, especially going for increased rather than
decreased range, don't say I didn't tell you it's dangerous, because I'm
telling you now. I am not a hardware tech.</disclaim>
The way around this is to go into that file and sort the modelines, not by
the way the come out of the box, but by final pixel resolution. Within that
grouping, sort them by dotclock (the first number after the modeline name).
During the startup phase for X it may even announce some details about what
your monitor likes best. (Under gdm these go into a log file. Under startx
they are left on your controlling terminal, unless you redirect to a file,
which I recommend.)
Anyways if you can figure out what line it is currently trying to use for your
resolution, you can comment it out, and force it to try another one that fits
the Hsync and Vrefresh restrictions. If you run out of usable lines, that
mode won't be provided anymore. Um, and don't be afraid to use
ctrl-alt-backspae (the zap combo) to bail out of an X session that looks
I *do not* recommend doing this sort of experimentation while you have X
under xdm/gdm/etc. display managers. If you prefer that sort of thing,
set aside a runlevel that doesn't do that, and while you're doing all this,
change inittab so this new runlevel is the default. You may have to reboot
several times if your laptop is really fussy, because a broken X loves to
wedge the keyboard.
I *do* recommend that you try this at home, or while you otherwise have a
lot of time on your hands, because X takes a while to start and you're going
to be restarting it a lot.
* Heather Stern * star@ many places...
- my dell
- From: "Jordan Evatt" <email@example.com>