High FPS @ 4K with highest settings... well sounds like you need two high end graphics cards such as GTX 1180 (TI), yet to be released 🙂 As for the CPU to allow those graphics cards to reach their potential, you are going to need a CPU with fast cores and a reasonable number of them. You might like to look at Intel i7-8700K... 6 cores that are pretty much the quickest out there. Even with all that grunt, your mileage will vary game to game.
Regarding CPU optimized for work station... it depends what sort of work you are doing and software you are using. Some workloads can take advantage of many cores and you can spend thousands of dollars on multi CPU setups. Other workloads/software don't need anything special... an i7-8700K...