This is a simple question! I've been out of the desktop graphics card game for a little bit and I am trying to figure out if modern cards do HDMI audio pass through, and if so, generally how this works.
I've spent a bit of time googling around for this and I've found out that some older cards used spdif cables from the mobo to the card for audio over HDMI... after that things kind of get murky.
So is this a common feature now, and how does the audio get passed to the video card?
Yes, this is common now with any graphics card that has an HDMI port. The newer graphic cards have an audio processor just like your motherboard or sound card would have. Once the drivers for the graphics card are installed (including audio), your operating system simply sees it as another audio processor and, if selected as the default audio device, sends the audio signals to be processed by that device.