Xorg Mach64 DPMS: invalid scan freq

Michael Nottebrock lofi at freebsd.org
Mon Oct 24 11:19:10 PDT 2005

On Monday, 24. October 2005 04:54, Rick Voland wrote:
> I have Xorg working fine during normal use, but I get a warning message
> "Invalid scan freq" on the monitor as the video system approaches DPMS
> power down mode.  This problem has been mild and only occasional with
> recent versions of Xorg, but is very noticeable in the latest version
> (xorg-server-6.8.2_6).

If your monitor actually manages to display a message, it's pretty safe to 
assume that whatever input it is getting that it does not like will not 
actually harm it and it is in fact safe to ignore it.

> The system is fine during full power mode and during the initial
> blanking of the screen which starts after 10 minutes of no activity.
> The warnings occur after the simple screen blanking and before the
> actual DPMS power down.  In the past, the system successfully reached a
> DPMS lower power mode even after these warnings, but I am reluctant to
> test it now that the warnings are prolonged.

My guess is that either your monitor does not handle one of the three DPMS 
power states correctly or that there is a bug in the mach64 driver or perhaps 
there's even a hardware problem with the graphics adapter itself. Either way, 
you can probably work around it by skipping the respective power state.

You can do this with the xset utility, if your window manager/desktop 
environment does not bring its own facility to control the DPMS timeouts.

The usage is: xset dpms <timeout until standby> <timeout until suspend> 
<timeout until off>

'off' is the mode with the least power consumption, the unit of the timeout is 
minutes. Specifying 0 will disable the respective mode. You can test which 
mode triggers the warning on your monitor by testing each mode invidually at 

xset dpms force <standby|suspend|off>

My personal guess is that it is 'standby' which your monitor does not like.

   ,_,   | Michael Nottebrock               | lofi at freebsd.org
 (/^ ^\) | FreeBSD - The Power to Serve     | http://www.freebsd.org
   \u/   | K Desktop Environment on FreeBSD | http://freebsd.kde.org
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