Ok I've figured it out. If you overclock too much and VPU recovery kicks in, it changes your CCC profile so that 2D clock gets switched to the 'medium' 500Mhz setting and your 3D voltage is also LOWERED by about 0.02v.

I was at around 1.17v with this bios in 3D before, after VPU recover + 500Mhz 2D switch, it dropped down to 1.15v.

Always delete the CCC profile files after a VPU recovery!!!

Stupid ATi drivers