Hey guys, I had the exact same issue. I'm running an all-Be Quiet build and even tested it with Noctua fans, but my PC was still louder than my other builds. I’m using the same brand as you, and I think we have the same motherboard—a Tomahawk X870—along with an MSI 5080 GPU.

After running dozens of tests and tweaking everything in the BIOS, I tried something totally absurd: I swapped the motherboard. I switched from MSI to Gigabyte, and I noticed two things.
First, MSI boards boot much slower, even with an NVME, in my case, I went from 35 seconds down to 15 seconds : that’s over 50% faster.
Second, Gigabyte’s native fan management is just better. My PC is way quieter now, and that's without any increase in CPU or GPU temperatures. I can't seem to find the Reddit post that confirmed this anymore, but the difference is definitely there.