There's another way that does not involve removing drivers.
The "secret" is that Windows can only use ONE audio output device at a time, so you get to specify which one. When you install a new video card with HDMI (or other) outputs that carry sound, too, the video card also has its own audio output chip, as yours does. Very commonly, the card's Install process installs both video and audio drivers and then sets Windows options to USE those new devices. In your case, you need to change the Windows default audio output device.
I'll give notes her base on Win XP, but later Windows is very similar. Click on Start at lower left, then Control Panel ... Sounds and Audio Devices. Click its Audio tab. The top box labeled Sound Playback ... Default Device has a drop-down selector window. Click its down-arrow and choose the system on your mobo (ROG Supreme ?) and not the one on your nVidia card. You can make similar selections in the other boxes if you wish. Click OK at the bottom and back out of Control Panel. You MIGHT have to reboot to get this to work. But now Windows should be sending audio out of your mobo's back panel ports rather than from your nVidia card ports.