I'm using 12.1 drivers with the runtime from 11.11 drivers (SDK 2.5.793.1), which is the latest 2.5 sdk. On a 5850 with phatk V2 W256 (970 core/150 mem), yields ~400MH/s.
Also, how do the driver not matter? It includes an updated runtime
... which will only be installed in case you select it.
No your just missing the point I was being sarcastic 5 posts ago. It's called a rhetorical question. The point being there is nothing wrong with sdk 2.6
SDK 2.6 is useless for anything else than GCN (series 7xxx) atm, since you are required to mine at stock ram clocks, while SDK<=2.5 means you can massively underclock ram and highly overclock the core.