The best way to gain more hashing power with lower temps is overclocking GPU while downclocking memory while FAN is set to 100%!
My example is:
-Before mem downclocking-
As I've said I was using Phoenix+Phatk
Yesterday I udated to Catalyst 11.6+Phoenix 1.50
And here are the test results:http://forum.bitcoin.org/index.php?topic=17379.msg224049#msg224049
Another thing that I would recommend is to change the thermal grease. I saw some cards where there was so much of it or it had already become dry causing overheating up to 100C with stock settings.
The 1st thing I've done when got my cards after testing them was reapplying thermal grease on all of them (used AC-MX4). After these manipulations I got the temps lower up to 2-5C depending on the card.
Your GPU 2 may just have bad contact with the heatsink or some thermal compound problems.
Just try downclocking your mem and post results. We will find the solution!!!