Most Import Hardware in Server for Cracking RainbowTable. GPU vs CPU

I am a network engineer, specializing in wireless. I am getting into pentesting wifi specifically while practicing for certs like CWSP and GAWN, but in the end I want to maybe find a postion to bridge my security and wireless skillsets. Anyway.. I need a build a new lab machine in general and since I plan on doing alot of WPA2 cracking, I want to make sure my new build is time efficient. So what element in the build is more impactful in getting faster cracking results against a rainbow table, CPU or GPU? I will already have 32GB ram for other network simulation and vm's like EVE-NG or GNS3. So should a even bother with a GPU and invest in 32cpu server cpu or will adding a GTX or RTX card help out more? I know BTC mining back in the day was more CPU, the GPU, now ASIC, so hardware actually is most beneficial with decryption?

Thanks..