I have a computer I built which has been rock solid for around a year or so and recently has been blue screening on me. When I do the usual spot checks I use new thermal grease on my H100i cooler. then do a stress test. I can see my default temp is around 50 which is a little high but it's been warmer than usual so I put it down to weather. when I run the stress test I can clearly see the CPU reaches 100c within a second of starting the test. This being odd for an H100i, i7 4770K not overclocked PC.
I try other tools and think its dodgy sensors. I then try a bootable USB Linux disk and do the same tests. To find out my Core temp at idle is 32 and my Prime95 stress test (small FFT's) is 60 odd. completely normal. Windows is incorrectly detecting my CPU temps. And I have no idea why. As you can see in the other image my PC will Jump Stright from 40-50 (which is higher than normal anyway) to 92-100c