I have updated my gist with more test reports when OPENBLAS_CORETYPE="Nehalem" is fixed as an environment variable. Note that on this machine, OpenBLAS detects the "Barcelona" core type. I used the following ctypes based script to introspect the OpenBLAS runtime: https://gist.github.com/ogrisel/ad4e547a32d0eb18b4ff -- Olivier