hello! i have run test with the lowest value on "core voltage" nothing happened ...i still have the jumping temperature every second...in games the fps dropping from 60 to 2...i don't know what to do anymore...this happened after i change the paste on processor and video card (i change 3 different pastes) same problems...lenovo g50-80 with I7-5500U 2.40 Ghz
What are you using to adjust these voltages? If you are using XTU, your processor is not supported.
Also, you should be concerned about undervolting:
You didn't answer. Was it doing this BEFORE you replaced the TIM? If not, then the replacement of the TIM is what caused the problem. Are you sure that the processor is staying equally clamped down from all four "corners"? Before applying the TIM, did you completely and thoroughly clean both the surface of the heatsink and the surface of the IHS?
[Aside: if you lifted the heatsink to check the TIM, then you need to replace the TIM again. Think of this as a rule: Once you unclamp, you have to replace.