After trying many compiz config tweaks found under other answers, I looked at dmesg and found the following:
[ 36.361815] [drm] Wrong MCH_SSKPD value: 0x16040307
[ 36.361818] [drm] This can cause pipe underruns and display issues.
[ 36.361819] [drm] Please upgrade your BIOS to fix this. –
Looking at Lenovo's site: Lenovo support for T420 There was a bios upgrade available for my machine released on the 17th of July, 2013. After running this update, the video works as in 13.04.
I had trouble with the same type of system. What finally got me working was to disable the acceleration support in the nouveau driver. Via sudo, I edited /etc/defaults/grub so that:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
Became:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash nouveau.noaccel=1"
And then:
sudo update-grub
I restarted the machine, and the graphics issues were resolved. Admittedly, I'm disabling the acceleration support - but I'd rather have slow correct graphics than fast incorrect ones.
In my case, the issue was that I'd have color corruption (in some cases, full white out) on icons and in terminals. At first I tried disabling the display compositing (Settings Manager -> Window Manager Tweaks -> Compositor). That helped a bit, but I still saw numerous issues.
I attempted to figure a way to install the nvidia driver, but my understanding is that I need the 96.43 one. The .run file from nvidia doesn't work for newer kernels, and I gave up on that approach after a while. I attempted to find a repository with a recent 96.43 package, but had no luck. My guess is that folks have better things to do with their time than update packages for drivers that support cards that are roughly a decade old...
Along the way, though, I had noticed that rdesktop had no display problems. I figured that the code there likely wasn't calling for acceleration, so I figured it was worth trying to disable it.
Best Answer
The high CPU use could be due to fallback to the software renderer. You can verify whether or not you're using the software renderer by executing the following command on the command-line:
If the result is as follows:
That indicates that the software renderer is being used (nice use of a double negative there). In that case, installing the latest version of the Intel graphics drivers, as recommended in another comment, should help. However, as of November 28, Ubuntu 13.10 is not yet supported by the Installer. It appears to be one of those "any time now" situations.
In the meantime, I was able to fix the problem on my system (ThinkPad T420S) by installing the drivers via the oibaf ppa which supports Ubuntu 13.10. unity_support_test now verifies that software rendering is disabled. Hope this helps and let us know if you managed to fix the issue, as well.