MinDesiredFrameRate=

[Harmatia]

I'm sure some people already know this, but I haven't seen it said conclusively anywhere exactly what this does.

If you go below your desired FPS, it disables dynamic lighting, such as the lights below a rocket, or the flashing blue or green when using a stinger or link gun. Very useful for those of us who max out FPS on some maps, but drop below our caps in heavy action; set this to the same as your cap and as soon as you start dipping below it dynamic lights will be reduced.

It doesn't affect dynamic shadows, as I've heard others say (as far as I can tell).

[Brad.G]

MaxSmoothFrameRate=

Caps your FPS which can be good in some sense if your rig isnt up to keeping high FPS.

Rather than letting your rig fly along with 80 FPS, but then getting in to heavy action and it reducing down to 30 FPS, you could set this value to somthing more suited to your computer. for instance if it was capped at 50, it would only be dropping 20 FPS which is less noticable than when it was dropping 50 FPS before the cap was implemented. Also as a rule this shouldnt be set higher than the refresh rate of your monitor. most TFT's are around 60, but there are some which are alot higher be sure to look in to it

[Harmatia]

MaxSmoothFrameRate=

Caps your FPS which can be good in some sense if your rig isnt up to keeping high FPS.

Rather than letting your rig fly along with 80 FPS, but then getting in to heavy action and it reducing down to 30 FPS, you could set this value to somthing more suited to your computer. for instance if it was capped at 50, it would only be dropping 20 FPS which is less noticable than when it was dropping 50 FPS before the cap was implemented. Also as a rule this shouldnt be set higher than the refresh rate of your monitor. most TFT's are around 60, but there are some which are alot higher be sure to look in to it

Yup. For some reason I find that the default of 62 actually results in less tearing than 60 on a 60 Hz monitor.

This is useful for the situations where you drop below your cap, as it removes some lighting effects on the fly... usually during heavy action where you wouldn't notice... keeping the FPS at the cap and nice and smooth.

This, along with a cap, can keep your FPS at the cap even more often.

[Ahura]

So really, it is just your monitor. I believe you can force your LCD to refresh more via GPU, just don't think it worth the bother.