The needs will vary greatly depending on a number of things, including:
Amount of servers active
Tickrate values
Map size (amount of islands)
It's been our experience that the Atlas servers tend to favor higher clock speeds, more-so than ARK does. The resource demand has progressively lowered since the server files were released. The updates coming out over the next few weeks are said to improve server performance two-fold.
What is your CPU usage looking like on a per-thread basis?