I just bought a new computer with a i7-7700k, ryzen 580, 16gb ram, 650w power supply, and a Z270 MSI motherboard. I have installed fortnite and counter strike and I average above 144 on both easily. After installing Rainbow Six Siege I get on average 100 fps but it spikes every 3-4 seconds down to 30-40 fps. In the settings it says that it is using my graphics card but I don't know why the fps constantly spikes.