When you say the cpu is working do you mean the fan is spinning up, but you are not getting a post beep? That is very odd. I do not see how the CPU would be getting power if the motherboard is fried. It is possible that the motherboard is toast. Have you tried removing all the components except for the CPU and booting?

What kind of video card do you have? Do you have onboard video as well? Do you have an old video card you could use to test?