It is overheating and throttling itself to avoid damage.
Set up a fan curve so that it never exceeds 69*c if you don't want that happening.
According to HWmonitor, temps never get above 61c. Games run fine (been playing Metro 2033 and Arkham city, both games are way more demanding than dragon age. ) Ran OCCT GPU for an hour with no error. Ran 3DMark 11 bunch of times with no crash.
I am also using the latest 13.1 driver.