My sapphires are quite stable at 0.85v up to 780MHz. Helped the GPUs to not go above 75C at 60% fan speed. I can't get past 800MHz @ 0.95v though, had to use 1.0v for it to be stable up to 840MHz.
Wow, your temperatures seem extremely high to me.
I just remoted into the rig and this was it's current temp readings. 3x 5850 1x5830 all 825/150/1v
Ya they are really high. The only time I had temps like that is when a bunch of cards weren't using riser cables, and there was no space between them for the fans to work. The fans were running at 75%, but hardly moving any air.