Question CPU fans started running hard, temp fluctuating on i7 (just replaced motherboard)

[nutshellml]

Morning all. Having some issues with my fan running and cores running hot.

Background:
I have a Dell i7 8700 for about 5 years now. About 3-4 weeks ago I bricked my motherboard with a DELL update. I found the exact same motherboard used, replaced it, and everything was perfect for weeks.

Issue:
All of a sudden, my fan started running very loud, I downloaded CoreTemp and realized my core temps are running very hot. I opened the case, all fans are working. I'm not sure what the issue is. It will run really hot then slowly cool/slow down then back up if I try to run anything. Now even idling it still jumps very high (see screen shots below).

I'm not sure what to do. The CPU fan seems to be working fine, I also touched the heatsink when it said the cores were hot and they weren't hot...

Any thoughts?

Screenshot TEMPS

 

[zirging]

The thermal paste is probably rock solid and needs to change. The increase and decrease of temps is due to the thermal throttling, it bassicaly lowers the clock to decrease the heat output and when it is cool enought, it starts increasing the clock again and that goes over and over.

 

[nutshellml]

The thermal paste is probably rock solid and needs to change. The increase and decrease of temps is due to the thermal throttling, it bassicaly lowers the clock to decrease the heat output and when it is cool enought, it starts increasing the clock again and that goes over and over.

Thank you! Ive read that one a few forums. I'll grab some from local computer store!

 

[Paperdoc]

Look around here or ask at the computer parts shop for advice on HOW to remove the CPU cooler system from the CPU chip. If your old thermal paste really has hardened, it may be very difficult to separate them unless you know some techniques. Once you get them separated, you also need a few hints on how to clean off all the old paste. THEN read carefully exactly how to apply the new stuff. Each CPU chip needs a slightly different amount of new paste, and you you need to follow recommendations. Too little is not good, of course, but too much actually can be a problem when it acts as an insulator.