The FPS I get depends on allot of different factors. That being said im going to give an average based on playing on the asylum servers.
On average I would estimate that using all ultra settings with some post processing effects turned off at 8000 view distance and a 2560x1440p monitor my frame-rate is between 50-95fps depending on where on the map I am.
Honestly for arma I cant stress enough that the best route is INTEL! and nvidia. Get a good single thread performance quad core processor. (Dont get the new i9's) Don't even bother with AMD. Its not necessarily about which is better but arma has always run like shit on AMD.
Full build can be found here: https://ca.pcpartpicker.com/list/bgBCnn
Processor (CPU): Intel Core i7-6700K Quad- Core overclocked to 4.8GHz (Corsair H100i GTX AIO Watercooler)
Graphics Card (GPU): MSI Geforce GTX 1080 Ti Gaming X non overclocked
RAM: G.Skill Ripjaws V 32GB
Storage (HDD/SSD): Samsung -950 PRO 512GB M.2 SSD (Read speed 2500MB/s)
Power Supply (PSU): Corsair 850W PSU
Software: Windows 10
Arma 3 Build: Screenshots of setting below