The original ThunderX was up to 96 cores in 2 sockets, but single core perfomance was unimpressive (comparable to Cortex-A72).
ThunderX2 is 64 cores in 2 sockets, with 4-way SMT, up to 3GHz turbo, and the cores are way better.
// It's great that they're competing with dense rack servers, I just wish the low end to mid range market wasn't ignored :(