Audio randomly cutting out/Black screen during boot

Hey guys,

So I've just completed my first hackintosh build. It's running great and much faster than my iMac. But there's one major problem: sometimes audio randomly gets cut out for one sec, both when using the internal realtek sound and a FiiO K3 USB DAC. Really annoying, since I plan on replacing the iMac with it and listen to music on it.

Another problem is that the monitor turns black during boot, and after a while it turns back on showing the login screen. Also the menubar on my secondary displays became opaque white. I've heard this is a unique problem of Navi GPUs so I applied the kext patch, but it doesn't solve the problem.

Please help! If needed I'll attach my EFI.

Complete parts list: https://pcpartpicker.com/list/NWnWHB