actually, update your flash. the new version 10.2.smthn.g fixes this issue. (Youtube has flash videos u know) The older version forced the card to use the 'multimedia' clocks set in the VGA bios, the new version is more relaxed and lets the card to speed up to max when it detects proper 3d load.
I'm still on the older flash version because I'm abusing this 'feature' with GPGPU BOINC stuff to keep it nice and quiet when under load.
edit and just to clarify
there are 3 different clock settings in the bios, idle 157/300, media 400/900 and full 3d 850/1200 or w/e the oc