We do not recommend you do the "baking" trick at all really as it causes more damage than good. For one thing, each time u heat it up like that, more and more oxidation occurs and builds up on the connections, degrading their quality more and more with each subsequent overheat until the unit no longer boots at all.
Now another thing is that every CPU and GPU have a max operating temperature that they must not exceed while being powered. For most current processors the limit is usually somewhere between 75 and 100 degrees Celsius until critical damage starts to occur. Now when the unit is off, this is another story and it is perfectly fine for it to reach over 200 in order to be reflowed properly.