some issues with kwin 4.9.2 and nvidia drivers 310.14
this is my first post, although i've been a reader/lurker for years now
i've also been using kubuntu for a long time now, even in the dark years of the early 4.x kde versions...
Anyway, i have two small issues after upgrading to 12.10:
first one is some tearing on the upper part of the screen, kind of just one line, but it is noticeable if you grab windows around, and it affects video too. vlc has tearing both in windowed mode (less) and in fullscreen (more). kmplayer behaves the opposite; fullscreen is perfect but windowed has the same issue. I have vdpau enabled in both. btw i tried every possible combination of vsync in nvidia-settings and kwin settings and both on gives the aforementioned result, which is the best i could manage. every other setting gives me "regular" tearing all over the desktop.
sidenote: the same configuration was working with no issues on 12.04
second problem is the dreaded flashplugin (installed via flashaid) ... i managed to activate hardware acceleration with nvidia-experimental (i guess they were 304.43) but as i enabled xorg-edgers repo and installed 310.14, flashplugin fell back to software decoding and presentation. i really have no idea why... and i tried every combination of the HW accel. tickbox and mms.cfg.
My relevant setup: Kubuntu 12.10 64bit with kde 4.9.2, nvidia blob 410.14, card is a 660ti
I am also experiencing this issue on my setup as well. I am using the 310.14 driver as well, but I am using Gnome Shell as my DE. There is one line of tearing about 1/4 down the screen. It is present in desktop operations, fullscreen video and games. I have OpenGL vsync enabled in the Nvidia settings. Any word if the latest 310.19 driver has this issue as well?
yes the issue is still there even forcing max performance on powermizer (although a lot less)
by the way i'm on 310.19 now but the problem has been there with all 300 series blobs.
I thought it was a kde specific problem but now i see it's a general compositing problem.
the good news (at least for us kde users) is that kwin devs are working over it, and i think i read somewhere that nvidia also is looking into it.
This might be because GL VSync doesn't play well with KDE (it results in problems with my 560 Ti) and you cannot really prevent GL Vsync being enabled in Ubuntu. Ubuntu uses a *.desktop file to load nvidia-settings at startup rather than an xinit script, which runs too late after KWin has already loaded.
So try using an xinit script instead to run "nvidia-settings --load-config-only", disable VSync in nvidia-settings and enable VSync in KDE system settings/desktop effects and restart X11.
Another method is to kill KWin and restart it without logging out; that should make it use the current VSync setting rather that the startup default.