Can it be that crashing cards has something to do with the tower that you connected to / your location
I am in CPT at the moment and have had 5 card crashes in 24 hours. In JHB I have not had a card crash in ages and have sometimes been connected in excess of 12 hours, so I am not convinced about the heat story.
I am not running the dash, straight networking connection.
P.S. Drove along M3 CPT last night with laptop on the passenger seat and talking on Skype to the UK, so coverage along M3 appears good.