Hi All

This is my first post here because I couldn't find anything about my issue on the googles and interwebs..

I have the Maximus V Formula and have been loving it so far. However when I updated my setup with a new mixer in order to make my twitch stream better I encountered a weird problem.
Until now I have been using a Focusrite 2i2 as my audio in/out. In order to use the mixer (a Yamaha MG12) I needed to pull audio from the 3.5mm jack outputs.
When I monitor the audio from the jack on the mobo into the mixer I can hear a noticeable high pitch sound.
To make it easier it goes like this:

mobo speaker out (green 3.5mm jack) -> Yamaha mixer -> Beyerdynamic DT770 = High pitch sound
mobo speaker out -> Beyerdynamic DT770 = No high pitch sound.

I know what you are thinking, the mixer is faulty right? Nope. Using my laptop, iPhone or iPod the same way I have nothing but good audio.

iPhone/laptop/iPod -> Yamaha mixer -> Beyerdynamic DT770 = No high pitch sound

The "weirder" part is, I have the two intel usb3 ports (the ones by the ethernet port) populated with my mouse and keyboard and when I pull the mouse and keyboard out from the ports, the high pitch noise is gone! I simply cannot understand what is happening. Especially when I get this from the ASUS website: SupremeFX IV – AMPed For Perfect Audio

Not really..

Am I the only one that has encountered this problem on this quite high quality mobo?

Keep in mind that I hear the sound when I turn up the volume to relative normal levels on the mixer. I have to turn the levels down quite a lot to avoid the noise from the computer.

I have tried all the 3.5mm jack out and inputs, both front and back with the same result.

Thanks to anyone in advance that has ideas or solutions as this is driving med mad! (sorta).

Best regards
Howk