I'm under the impression that you are very confused. What do you mean by that your CPU and memory(RAM?) have burnt out? If you mean that they're dead, then why would you want to replace the motherboard? I'm not sure about the whole Styrofoam problem. I've never heard of such a thing or have ever tried it.
What you want to do is try all your components on another PC that supports them and test them out one by one to see if any of them have failed.
To find out where your Front Panel connectors go you can have a look at your motherboards manual.