Thank you all for your response.
ahthurungnone, for my CPU voltage, i took these numbers from sites like techreport (overclock made by the editor), my cpu cooler looks okay for now, if i invest in something i would prefer buying an SSD drive to see my pc boot in half the time it takes now. My PSU is 600W but not 80 plus so i'm pretty sure it's not real numbers (paid it 50$ with 15$ discount...).
saint19, my CPU is an c3 revision. SPU? you meant PSU?
use the settings that you find on Internet. Why? Because even with the same hardware, you will not get the same overclock results. Just read the basic things and do it your self, overclock is test-fail.
2- Yeah, I mean PSU, but for the price that you say I'm pretty sure that you will need a real PSU for Crossfire.
3- For your C3 and the 4GHz you maybe need a voltage between 1.4V and 1.5V. As always, keep your eyes in the temps and something equal or above 60ºC isn't good.