Why one of my core throttle so much?

[Marko9111]

HI,I have i9 7900 and 9 out of 10 core have great thermals when OCed,but one,that intel marked as one of two best cores is thermal throttling so much?Does anybody know what could be the problem? here is an example...
My CPU is delidded and I have placed liquid metal.
https://imgur.com/a/kzvZe
Deliddig and liquid metal placement
https://imgur.com/a/dmuNB

 

[cadejohnson01]

That core is getting too hot so its down clocking it to cool it off