Hey guys, over the past few weeks my blackbook has been shutting down more and more frequently from what I can only believe is overheating. I just checked my computer upon startup with SMC fan control - it starts up at about 70 C and at about 3500 RPM. Yet, after a few minutes, the fan immediately drops down to 1100 RPM or and fluctuates between 800-1400. I try to force the fans to spin with SMC Fan control, but nothing happens. I've looked all over the web and I can't find anything definitive. I know that macbooks tend to overheat. What can I do? I'm at college and I really need to find a fix for this as soon as possible. thanks.