Some good improvements here... I'm trying my card at 900/1800/2150MHz @ 1.075V and it looks stable... Today in the morning I've got some fans inside a shipment for a friend's build, and one 12cm for me... Jigsaw time then! I've opened a hole on the left side of my case, where before I had a small 8cm quiet fan, with its airflow somewhat limited by the case mesh too. After fitting the new larger fan with nothing to obstruct its airflow, temperatures dropped rather seriously. Even if run at low rpm (actually I'm reading 900rpm) the added airflow does very well its work.
Furmark, 875/1750/2150 @ 1.045V, old 8cm fan -> 76-77°C
Furmark, 875/1750/2150 @ 1.045V, cut 12cm fan -> 67-68°C
Furmark, 900/1800/2150 @ 1.075V, cut 12cm fan -> 71-72°C.
All those temps were made with the card's fan set to be controlled directly by afterburner, no ways getting over 65% of its speed. If you are having temp issues, check your airflow first
Those cards do make some heat, bad air circulation ends into having an hot air bubble around your card keeping it hot
will post some pics soon.
edited my chart of user's cards here TPU's GTX460 Club