How to know if your computer has been set to overclock?

Thermal paste not applied correctly.
The heat sink not making good contact(not installed right).

Basically what ss202sl said, try reapplying the thermal paste, and while you're at it re-seat the heatsink. Also make sure your case has adequate airflow. It could also be a dead CPU fan.

Ya, if the fan is spinning, it's working. did you put any thermal paste down ? what fan, what motherboard.

O.K> I bought a new fan, the seller sent a tube of thermal paste with no markings on the tube and not one word of information in the package.(before your answers appeared) I assumed it was for the fan and put a dab in the fans well. Did not know anything about a heat sink yet and the fan replacement was made without removing the heatsink.
It runs, but will the thermal paste ruin anything MORE than the fan? I ran it for 3 days before realizing the tube was not for the fan, but was thermal paste and I goofed. Stopped using it and want to know if I might have ruined anything else besides the fan. I will get a new fan now, replace the heatsink paste if you all think the computer is still ok.
I have asus A8Js laptop with gaming card. Also, do you think the seller should send me another fan at no charge since they lead me to believe the tube was oil for the fan by not having the tube labeled and no note to explain what it was? I only bought the fan , not the heat sink. How was I supposed to know? I never even opened up the case of a computer before now. I am just an ignorant consumer.

Also: If my computer time is exact with real time, does that indicate it is NOT over clocking?

Thanks everyone. I bought a new fan and ready to do as you all suggest. I have learned how to clean surface and apply paste, but don't see how to get the heatsink out to reset it.I would like to find a tutorial video or clear instructions on how to get my heatsink out of my ASUS AJ8S laptop. I cant find it. Can any one help? Also can anyone answer my question above this one about over clocking?