Dear friends,
According to my experiences, fan speed will be faster when your CPU increase, in your cases 76c+/- fan should be running faster because the temperature increase, should be normal.
For your cases, if u facing this problem again, when your temperature is increase, u must checking, are you running some program is in process or is your program is scanning your computer or something else which still in running ? for example antivirus scanning on background or some flash website also can causes your increase of your usage of process)
You can also check, what program is highly processing, go to task manager (Control+Alt+Del) and under windows task manager u can click Processes tabs, in processes tab u can see CPU column, short the CPU column, u can see what program is running not stop... usually program will idle when u not process and in idle mode when u did not touch it (if the CPU column 99 = full process , 0=idle) if you some program running 85 continuously even u did not touch it, end that program and u should see the temperature will cool down.
Please notice that if u are running DOS Application in your windows, your temperature will be increase due to the DOS application when running is consume 100% processing process for some dos application.
For some cases, if your memory is not enough for your operating software, it may also can increase your processor usage because convert memory in virtual memory.... you also need to check your memory too... if your memory is out , than conversion to virtual memory will delay your speed because data convert and store at your hard disk and increase usage of your process and increase temperature.
If u have verify all the program is idle and the temperature is still high, it's may be your hard ware controller problem.