You haven’t said what are you comparing the AMD 3900x to.
But generally speaking, it will be faster than any Intel CPU with less cores which doesn’t have AVX512 for Multi Threaded Linear Algebra.
It will be also a decent CPU for single threaded operations yet Intel has higher frequency CPU’s which will beat it on those tasks (Probably in the 3-10% range).
If you use it with MKL, remember to use the Acceleration of Intel MKL on AMD Ryzen CPU’s trick. Then you’ll get the best BLAS performance out there for non AVX512 12 cores CPU.