Maybe changing this setting
can do something for GPU 460 Mhz. It's still set like in default and it may be too big for 720p undocked.
It sets how fast game will change resolution when load is heavy
(I don't know if it works with this timing, I'm only guessing)
Code:
f.e.
1280x720 -1 sec-> 1242x698 -1 sec-> 1204x676
If you change it to 90.0 it will look something like this
Code:
1280x720 -1 sec-> 1152x648 -1 sec-> 1036x582
So framedrops will be much smaller, but changing resolution
can (not necessarily MUST) be more visible.