This maybe be caused for driver compactibility issues. You may be running drivers that came with your manufacturer, that time it may have worked fine. After that,especially after installing windows10 laptop starts getting too much heated, that's because Windows10 has updated your pc drivers to latest version which is not compactible.
Even i had same heating issues windows 10 and found that it was due to driver incompactibility. So I reinstalled drivers for windows from hp download page. Now my pc is not getting heated up and fan is running at normal speed.
try it!!!