X2 5000 BE & M2N32 WS problem with voltage

Hello, I have Athlon X2 5000 Black Edition and MB Asus M2N32 WS Professional. So I wanted overclock of course this cool CPU, but I have problem. I read in this article (http://www.tomshardware.com/2007/1 [...] verclocker) and they had to change voltage, when they wanted go higher then 15.5 multiplier. So I did it (on 1.475 V), but my PC never started again and I must resart CMOS. I tried heighten voltage of memory, but without success. Others options I have to AUTO, but I think that it isn't problem. But very interesting thing is it, when I changed voltage on 1.4 V (it's more then AUTO), but multiplier was still on 15.5, PC crashed too. Anyone know how I can continue in overclocking? PLS help THX