Does Manjaro (and the available kernels) support the AMD Threadripper CPUs?
The Threadrippers have been on the market for some time now, so I would imagine that the upstream kernel has also already supported them for quite a while now.
CPU support is chiefly a kernel matter, and thus if the upstream kernel supports them, then so does Manjaro.
there is some Threadripper with manjaro
I have searched for "AMD threadripper" and have found no thread.
In Dump your inxi -Fxzc0 here and bookmark it I found 2 inxi dumps mentioning threadrippers:
People are using them.