Re: Screen vibrates while using mouse or keyboard
On Fri, 26 Nov 1999, Bart Szyszka wrote:
> Hi,
>
> I'm having a problem here that's giving me a headache (very literally;
> the Blair Witch Project effect). While I type something in X11 or move
> my mouse, the screen vibrates as if someone is taping on my screen.
> I've run XF86Setup and xf86config several times with the same results.
Try adding the following to your lilo.conf:
append="no-hlt"
near the top of the file (before the first image reference) and run lilo.
And see if that clears the problem. If it does, you are having some power
supply noise coupling into your video cable or into the monitor itself.
What happens is that Linux halts the CPU where there is nothing to do.
When you move the mouse, type a character, or get data in from a network
card, the CPU "wakes up" to handle the event. This caues quite a load
spike on the power supply for the computer. You can sometimes also hear it
in headphones connected to your sound card when you move the mouse.
If setting the CPU not to halt when idle clears the problem, make sure
power connections between power supply and motherboard are in tight
contact. Make sure there is a good earth ground on the electrical mains
outlet, and move the video and power cables for the monitor away from the
cables for the computer. One of the problems is often someone that has
only ungrounded old US style two-prong mains outlets and installs an
adaptor but does not ground the tab in the three-prong adaptor to the
screw in the center of the outlet cover plate. That screw should (by code)
be earth ground on the older two-prong outlets.
You really want to resolve the problem and get rid of that no-hlt
statement because your CPU runs a lot cooler when it halts with nothing to
do. It also can save a LOT of power and make the CPU last longer. The
price you pay for having the no-hlt instruction may be random sig 11
faults if you do not have enough heatsink/fan to carry away the heat. This
is actually one of the reasons why Windows is so unreliable. It does not
halt the CPU and runs in a tight loop when it is waiting for more work
causing the CPU to run hot all the time.
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