Supreme Commander Forged Alliance Gigabyte Z390 Auros Master Fraps recording and crackling audio

When I record fraps video of Supreme Commander Forged Alliance, the video ends up with crackling audio. This happens whether the CPU or GPU is overclocked or not. My old Asus motherboards never did this. DPC Latency monitor says everything is fine during recording

Windows 10 build 2004
Gigabyte Z390 Aorus Master bios F11c

Update:

It happens on my Asus ROG Maximus XII Formula as well. I discovered it crackles only if my speaker setup is set to 7.1. 5.1 and stereo works fine.