7950 DCU II TOP can't overclock

[shockre]

Hi,
I just got 7950 DCU II TOP and I' trying to overclock it, but it just won't happen for some reason.
Tried with 12.3 & 12.4, both clean installs; GPU Tweak, Afterburner, Trixx, Overdrive; BIOS 1 & 2..
Every time I change clock and try it in benchmark/game - it freezes the whole computer and I have to hard restart it.
GPU Tweak doesn't even let me change voltages even tho I enabled range enhancement.
Trixx always says that ULPS is on and I have to disable it. And I do, but it says it's on again.

Any suggestions?

Thanks