Need help buying a rig, and not GPU based

[Skwerl23]

Hey team, so my main goal is to have hashcat and john crack passwords as fast as possible, but i'm not brute forcing. most the passwords i will attempt are 16 characters, but doubled. so i need to run a stdout of 8 characters, or so, and insert rules to those. I can't seem to get massive increases with a GPU over cpu on this method. 

Does anyone know the best rig for rules mixed with combinator etc... would a 32 core cpu setup outperform a gpu on this? Most the rules i use will require john to perform the final hashing, and i know this ISN'T john's forums, but i know you guys are experts.

Also note money is not a problem (but want to be smart). I was thinking an i9 7960x  or a dual Xeon e5-something

Any tips are much appreciated.

[undeath]

If money is not a problem find someone to implement your attack on GPU for you.

[Mem5]

GPUs (like 1070-1080-1080ti) are far better than CPU (even i9)

[soxrok2212]

Also worthwhile to note that Intel’s OpenCL runtime is crap for Skylake X. Haven’t been able to get my i7-7820X to run properly on Linux or Windows 10. There’s no reason to consider CPU cracking.