I made it work on 5 it seems : http://prntscr.com/grm9ed

upped the virtual ram to 80. Disabled On board graphics , connected Monitor  with HDMI to GPU0.
Without Team Viewer going the hashrate is slightly higher - around 10500.
Only 4 cards accepted some change on the slider. The 5th had HBCC on, and on/off was not doing anything. On the 6th one HBCC was disabled. It was not even possible to enable it.

Sadly ... that lasted only until the first restart.
After it - we are back to 4. And I can't get em to apply any HBCC settings on at least 3 cards.