Getting ready to blow up my computer

So your computer has a switch on the back to let it accept both 220 and 110. Josh flipped his switch on his, plugged it in, and it melted his case and blew up his power supply. So, he assumed mine would do the same. It didn't. My computer worked perfectly, but for the inaugural run we put it outside just in case. I'll tell you why mine worked and his didn't--I have a Dell and he has a 200 dollar e-machines computer.