Comment 25 for bug 151674

@mardi
Well I was wrong, I got confused. I think it was a mixture of 2 things. First depending on my mood I switch between vsync and none vsync, sometimes I could tolerate seeing a big tear and sometimes I couldn't so felt happier seeing random mini tears for a split second :-). Secondly I had recently cleaned behind my computer and in the process plugged my monitors into different ports (without realising it obviously). Testing this today I found that when I switched the monitors from one port to another the tearing jumped monitors. Previously my setup was below.

DFP-0: 1280x1024 (Sony 17", no tearing, only used for DVDs when watching while working, so half paying attention ;))
DFP-1: 1680x1050 (LG 22", this is where I had the tearing, annoyingly the monitor I use for DVDs when chilling with people)

I swapped the cables so it is now the opposite.

DFP-0: 1680x1050 (LG 22", no-longer tearing, even composite effects are not tearing)
DFP-1: 1280x1024 (Sony 17", now tearing, including composite, which means its atleast tolerable now since I only use this for video when half watching :-))

So it seems the refresh rate info for the DFP-0 monitor is used (not the default monitor that can be configured in nvidia-settings). I would guess that the monitor your getting tearing on is DFP-1 (or atleast is in the secondary monitor port, not the primary). Might be worth a try, as if this is the case I think its likely this is all down to nVidia, seems too closely tied to twinview related stuff to be xserver compositing or kwin/compiz (again even with the new set up, when I changed to just single monitor mode for either monitor the tearing stops, as that monitor then probably becomes the primary device regardless of what port it is plugged into since the other is not active). I am sure I read somewhere about twinview by default using the default monitors refresh rate for vsync.

Adam