Just recently, I downloaded and installed the beta version of Speedfan (4.48 beta 6), and I have noticed at times a rise in the CPU temperature.
So what do you think is causing the rise? I will tell you..
Task Manager shows it as being Internet Explorer 10, the desktop version. I have noticed that Firefox has the same effect in Windows 7..
The fix is easy enough. Close down IE 10 and restart it. Annoying but it works..