Right click your desktop and open the NVIDIA control panel.
under '3d settings' click 'adjust image settings with preview'.
then click the 'use the advanced 3d settings' option and hit apply
then go to 'manage 3d settings' on the left pane.
regardless if hl2 is on your list already, click 'add' and find the exe (...\Steam\steamapps\your@email.com\counter-strike source\
hl2.exe)
the ones in green are important, the other ones just leave default. the yellow ones you should change to 'on' if it lets you (some cards force them on if certain settings are changed)

i got kajira and taran to do this and it fixed stuttering + gave them fps
you need to do this for every game you play if it isn't performing the way it should. i do it anyways, you ALWAYS want 'max pre-rendered' frames to 0 for fps. make sure you have the latest drivers installed from
http://www.nvidia.com too
i also use a program that saves the priority level in task manager, so it always runs hl2.exe on 'high' and doesn't reset to 'normal' when hl2 is restarted.
http://www.prnwatch.com/download.html <-- the bottom of the page
PS. Since it's summer you should watch your new card's temp with GPU-Z. if it's getting too hot you can download rivatuner to control your fan speed through windows.. because hot temps will slow you down too (you don't want
over 70*c during full load)
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