i just checked it on manufacture website and it said that the voltage for my DDR2 is 1.8v.
Is it safe when my current voltage is 0.12v more than the spec on the manufacture?
And what about the cpu's voltage?
I think at stock the voltages looked fine, however, do not overclock with the voltage set to auto. It can set them too high and damage components. Look for an overclocking guide specific to your processor type (like core 2 duo) and follow that if you wish to OC. There is probably one in the OC section of this forum.