I will just copy and paste this answer made by CompuTronix:
Your stock cooler has popped one of it's push-pins loose from the motherboard, which is a common problem.
Here's how to troubleshoot it:
Remove the side cover and run your rig so as to duplicate the high temperatures. While monitoring the temperatures, push firmly against each corner of the cooler for about 20 seconds.
When you see a significant drop in temperatures, you've found the corner with the popped push-pin. They are deceivingly tricky to get them properly and securely seated and latched.
Please use this Guide: Intel Stock Cooler Installation Guide -http://www.tomshardware.co.uk/forum/338655-28-intel-stock-cooler-installation-guide
This should fix the...