Terrymraborn wrapping them in blankets that causes more problems than it's worth. There are a few different issues that can cause a red ring not just over heating. Anyhow the 100% fix is to reball them taking both cpu's off. The ghetto way that most people try to do the temp fix is by re-flowing it with a heat gun. This is not a permanent fix and the rings could come back the next day or not fix it at , or the system could last for a few months before crapping out again.
Actually pull the power cord from the wall and the disconnect the 2 parts of the power cord i had that happen bout a month ago its from a power surge the tech from microsft told me to do that