I get uncapped fps(500-1000 fps) in Rainbow Six Siege menus with enhanced sync on but a 75 fps cap with it off. I cant get higher than 50 fps in game. I already used DDU to get the newest version of the AMD drivers. Vsync is off in game and fps limit is also disabled in the settings. I have contacted Ubisoft but their suggestions have been useless. All other games that dont use uplay run really well at high frame rates. I use a monitor with a max of 75 hz. I have also monitored performance with afterburner and indicates that siege has 6% CPU usage at 4300 mhz and 0% GPU usage which makes no sense.
CPU: AMD Ryzen 2700x
GPU: AMD RX 580 Sapphire Nitro+
RAM: 16gb Dual channel Corsair Vengeance LPX 2400 mhz DDR4
Motherboard: Aorus B450 M AM4