Question Random seconds-long freezes. Why?

May 18, 2020
I apologize in advance if this is in the wrong category. I really didnt know where else to put it.

For some reason if I play a game on one monitor, and have a movie playing on another monitor, the movie will randomly freeze for about 3-5 seconds at any random spot at any time. I dont know why this happens. I have 2 GPUs in my PC. I tried playing the video on one GPU, the game on the other GPU. This still happens. This only happens when I'm gaming at the same time. If I watch the movies with no game running, the movies will not freeze at all and play smoothly through and through.

The random freezing only happens when gaming at the same time. Given that the 2 GPUs are a 2080S, 1660Ti, the CPU is a 3900X, with 64GB RAM, I feel like there's no excuse for this to be happening on this kind of hardware. Also, the game is on an SSD and the movies are on a seperate HDD. Again, the videos freeze randomly for 3-5 seconds ONLY when gaming. The game in question is BO3. Can someone tell me why this is happening and how I can fix it?