I tried to increase GPU voltage, it's helps on neoscrypt for sometime. Thread hangs not so quick, but on cryptonight it didn't helps at all. I use lowered clocks for my 580 cards. I use 1245MHz GPU clock. Lowering it decreases speed - and this is not good for me.
Increasing the voltage works well but it's not so good assuming ^2 power usage, so at home I can only lower MHz at GPU and mem. Ye, decreasing speed this way.