Can you disable c state c6 in your bios? If you want to make sure its not idle power savings, disable all of the c states and manually set your vcore to prevent it from idling down. You can just do this as a test.
Does any of this apply to your system? I'm not familiar with threadripper.
"None of the above made any difference. So, in conclusion, the only thing that helped was to set the "Power Supply Idle Control" to "Typical Current Idle". Haven't had a single freeze since then.
The only drawback is that the VCore doesn't drop to 0.4 volts anymore, but stays at 0.8 minimum. I can live with that - haven't seen the temps raise at all.
I'm still very much confused about the purpose of that option. Modern power supply units should all be perfectly capable of handling low currents, or at least since "Haswell" came out - there were some notable problems with its C6/C7 states.
If you're having similar freezes at idle, check if your BIOS has this option and try to set it. It might help you.
PS: None of this applies if you have overclocked your system or disabled Cool'n'Quiet. At that point it's pretty much granted that you have set your VCore manually."