Hoba.rce, thanks for sharing your information it us.
At this moment, some products are experiencing audio issues related to HDMI. You would be able to find additional information on the following link. The information provided was given by an Intel Engineer. https://communities.intel.com/message/218663#218663
We are working on getting a new BIOS updated in order to solve this issue. Customers with OEM systems have been able to fix the issue, updating the BIOS to the latest version available and with the installation of the latest graphic drives.
Sylvi_intel I think your missing the problem, it`s about losing the hdmi signal when using legacy boot with bios 0021 or 0025...not hdmi audio
I have the same exact problem and its making me crazy, for now i have installed win 8 with uefi since i cant get OPENELEC to install on uefi usb stick.
Downgrading to bios 0015 is not an option since it has usb boot problems.
Hopefully your looking in to the legacy hdmi problem