Time to replace the Thermal Paste?
I've had my MacBook 2.26 GHz Core 2 Duo (13-inch Late 2009) MC207LL/A MacBook 6,1 - A1342 for going on three years this December, I bought it used through eBay and it's been running great after numerous upgrades / replaced parts including the Cooling Fan so I know that's not an issue.
I've Googled what the normal operating temperature should be and it seems to be in the normal range but suddenly the range keeps changing from 104° F to 122° F ( CPU die ) with the exhaust fan running at 6200 RPM + - ( smcFanControl ) but not holding steady or dropping below that range. ( Battery power )
Same readings with iStat Menus -
The only app running right now is Safari and CPU usage is not abnormal , Background processes aren't out of bounds.
Sensors check out, Could it be time to replace the Thermal Paste on the heatsink ?