I have two IBM Desktop systems. One works fine and you hardly ever hear the fan. When use is heavy...the fan will be loud for a few minutes, but will slow back down (never stops, but...you know what I'm getting at) On the other, it's sounds like a tornado...and never slows down. There are only 2 fans in the front right in before the heatsink for both systems. These two systems are identical in every way...and I they are used for the same tasks. What do I need to do to calm the 'tornado'? Is it a bad heatsink? A bad temp sensor? Thermal Paste? What?