Black Macbook Overheating/Shutting Down

[Shotgun OS]

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.

 

[Pax]

Could be a number of problems.....

(a) 70 C is a bit hot for an idle Macbook. It should be more like 60 C or less. The overheat could be
- runaway CPU process:- look in Activity Monitor
- clogged fan
- bad thermal paste:- iStat Pro will diagnose this, see below

(b) 800 rpm is IIRC too slow for a Macbook fan. The fan should not IIRC go below 1500 rpm. Could be
- clogged fan
- failing fan

As a start point I would suggest two things

- reset your SMC http://support.apple.com/kb/HT3964. SMC controls fans among other things. It's a very long shot, but it can't hurt to try it.
- downloading iStat Pro (free) and posting a screen capture of it on here. Then we can take a look. Take the screen cap when your Mac is completely idle (eg reboot it, leave it 5 minutes with no programs open, then take the screen cap)