Well, I have personal experience with a passively cooled GT. I had it @ 700/2000, and had a 53c idle 70c load with the HR-03
I recently got a 92mm fan for it, which doesn't allow the load temperature to exceed 60c. I'm sure even if you wanted to go as far as volt modding the card, the HR03 could handle it.
I recommend getting the HR-03 + a super low RPM Scythe fan. I can't tell the difference with it on 100% or off.