which best graphic card to me ? any advice i have z640 work station

And what's wrong with that in regard to AE? What do you hope to achieve with a new card? If at all I'd buy the cheapest RTX that's available, but in light of users reporting issues with those all the time, it's probably not going to magically boost your system as you seem to expect.

Mylenium

Without any info on what GPU you currently have and what you consider bottlenecks nobody can advise. Given how limited AE's hardware acceleration is and that most functions still have a software-only fallback mode, chances are you don't need to do anything and whatever performance issues you may have simply once more come down to straightening out drivers and configuration options, not throwing more hardware at AE.

Mylenium