I cannot get a Stable experience in Apex Legends

I recently bought a gaming desktop and wanted to play Apex Legends on it. The PC’s specs are:

° CPU: i7-9700KF
° GPU: RTX 3070 TI
° RAM: 16 GB DDR4 (single channel)
° Motherboard: TUF B360-PLUS GAMING
° PSU : 650 Watts

At first, I thought it was a bottleneck issue. It might be true that there’s a small CPU bottleneck of around 16% at 1080p, but the problem goes beyond that. I can reach 200 FPS, but it’s never stable — it can drop to 80 FPS in a split second, and sometimes it even stutters.