Sounds like your power supply is faulty. Any OS should have minimal impact on heat produced or workload to produce that much heat. Many off-the-shelf purchased PC's are built to tight specifications and tolerances and this could be the case with your power supply. Try replacing it with a more powerful unit.
Also, check to see if you have not blown (or partially blown) the power outputs that are available on your motherboard. This can happen if you replace something as simple as a CPU cooler with a larger cooling capacity fan. The extra power drain destroys motherboard power outputs and you never know until it is too late.