[CentOS] LCD blanks out overnight

Tue Sep 9 13:57:44 UTC 2008
nate <centos at linuxpowered.net>

Joe Tseng wrote:
> I inherited an ancient Dell Latitude C840 and recently installed CentOS 5.2
> on it.  It worked fine for the most part, but when I left it overnight and
> came back the next morning, the screen blacked out and wouldn't come back
> unless I did a hard reset.  Even though I turned off all the power
> management settings and left it set like a desktop, the next morning after
> that it still blacked out.  I thought maybe it'd come back if I switched
> from X to a virtual text console, but that didn't do the trick.  Has anyone
> seen this and what do I do to fix it?

Is the machine still responsive? e.g. does the caps light key work? Or
is it frozen solid?

I don't know how many laptops it affects but my previous Toshiba laptops
had problems where if the screen went into power save mode about 70% of
the time the only way to get it to turn back on was to either reboot the
box or put it in suspend/sleep/hibernate and wake it up again. Toshiba
said this was a common problem across vendors that used multiple cores
in their laptops.  Microsoft released a fix for it for XP about a year
and a half ago(though as the fix was a specialized fix not a generic
fix that was pushed out to users I didn't realize it until after I
switched off of XP and onto Ubuntu, took a while until a version
of Ubuntu came out that could suspend/resume on that system). I could
not find any related fix for X11, so I just disabled screen blanking
in the X server.

It's been a while and I don't have that laptop anymore but what
I believe I did was add

Options "-DPMS"

To the monitor section of xorg.conf, see the man page for xorg.conf
for other DPMS related options.

Of course that just turns off screen blanking/power off, if your
system is crashing, that's another topic..