5960x stutter under load

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I noticed recently my PC will stutter badly when the CPU is under 100% usage.
I tried on another system with different motherboard and 5820k exactly the same what I did, and under 100% CPU usage the other system didn't show any stutter. Could it be a bad CPU/ Mobo?
I tried fresh windows installation, tried to restore bios default and still the same.
I recorded a video showing the stutter.
https://youtu.be/TXe5iVNx9SE

 

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Today I got another board to try (MSI X99A Titanium) and the difference is very noticeable, stutters and lag completely gone under 100% CPU usage compared to the X99 Taichi.
I still like the X99 Taichi layout more and easy to work with the bios and OC'ing and it has better M.2 compatibility with 2 ports.
Do you guys think if I get a new X99 Taichi it won't have the same bad performance of the old one? Could be it is related to motherboard design? it is really weird, I never saw that symptom before.