Hi, I am going to build a new workstation in near future. My main requirement is simulations. any advice what to buy .., Budget is $3000.

thanks

Maximizing RAM and CPU cores should be your focus, not so much single core or GPU performance. You could build a pretty powerful system for simulation using an AMD Threadripper (16 or 24 core) with 128GB of RAM with that budget. The 32-core Threadripper might be just out of range of that budget.