I thought I'd make a single thread to discuss this issue since we're all over the place on this one. I know I can figure this out despite me not having a flickering TB on hand. This should make things easier to keep track of things here while I offer suggestions and you guys report back.
My theory is, after googling around, that there is a power management issue that may or may not be related to the GPU clock.EDIT: SOLUTION HERE:
The solution is to force the display to modeset to 1024x768@76Hz during startup by adding a kernel boot parameter. All these commands must be done as superuser. Either login as root in a terminal or use sudo at the beginning of each command if your system is setup that way.
1) Edit /etc/default/grub with your favorite text editor, such as nano, pico or vi. It would be wise to make a backup of this file first.
cp /etc/default/grub /etc/default/grub.bak
2) Add video=1024x768@76 to GRUB_CMDLINE_LINUX_DEFAULT between the quotes and separate with a space character if there are existing parameters. For example if yours looks like this:
then it should end up looking like
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash video=1024x768@76"
If there is nothing between the quotes then this parameter can be on its own.
3) Update grub so that your changes will be used on next boot:
Pay attention to any errors. If anything looks wrong then review your changes to /etc/default/grub for typing mistakes and update-grub again until you're all clear.
4) Reboot your system
The problem should be solved.
EDIT 2: SOLUTION 2
I've determined that it is just the fact that a resolution change takes place that shocks the display into working properly and not specifically setting KMS modeset to 1024x768@76Hz. Even just turning the display on and off with xset can reset the hardware into fixing the flickering issue. This is an alternate method that would load a script after you login to your desktop environment and might work better if the first solution doesn't work.
sudo nano /usr/local/bin/resetdisplay
and paste the following text inside, save and quit.
xset dpms force off
xset dpms force on
Make it executable:
sudo chmod +x /usr/local/bin/resetdisplay
Find whatever method your OS supports to make it autostart. Examples on how to do this are here:http://xmodulo.com/start-program-automa ... sktop.html
Add /usr/local/bin/resetdisplay as a command or application to startup automatically. You may still experience flicker during the login screen but should be fine after you login. The screen may flash briefly as the display is switched off then back on.