Re: 6800GT Bios updating.
This use to happen to me ONLY when playing HL2. When I had it at stock speeds, it would do it after 40 minutes of play so I didn't mind it much. Then, I OC'ed my card and it was doing it after 10 minutes.
I replaced my stock cooling with a Zalman and it hasn't happened since.
I suggest getting a Zalman over the NV Silencer. Silencers are known to not effectively cool the core. Read reviews and see for yourself.