ASRock 970 Extreme4 - no sound + confused audio ports?

[DentalAppointment]

Hi. I have seen a few similar threads but no definitive solutions, so I am creating a new one. Would appreciate any help very much.
I've just built a new machine with a 970 Extreme 4 board, and almost everything is working now except sound.
I have Windows 8.1 installed as well as new Realtek + THX audio drivers, and I'm running BIOS P2.60 with HD Audio enabled in UEFI. Here are the symptoms, and potentially related info, as far as I can tell right now:

-I get no sound output when plugging my speakers into any jacks/ports.
-They speakers work on the laptop right next to the new computer.
-DirectX does detect the audio hardware.
-When I play sound on YouTube, I can see the audio levels rise in the Speaker configuration window accessed through the taskbar.
-When I plug headphones in to the front jack I get no sound either. I have tried enabling and disabling front panel detection.
-When I plug the speakers in to the lime green or light blue rear ports, it will sometimes alert me that I have just "unplugged" an audio jack, rather than plugged one in. It's not consistent, but the detection seems to be confused or reversed.
-Front panel USB 3.0 works, but front panel USB 2.0 does not work with anything yet.

Anyone have ideas regarding these symptoms or a potential fix?
Is is possible I don't have the pins connected correctly? Or likely something else?

Thanks.

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ASRock 970 Extreme4
AMD FX-6300
Corsair Vengeance 4GB + Corsair XMS-3 4GB (dual channel)
Kingston V300 120GB SSD
Corsair 500CX PSU
Sapphire R9 270 Dual-X GPU
NZXT Source 210 Case
Windows 8.1

[Tweakurr]

Right click the speaker icon in the tray, choose Playback Devices. Look at the list and see which one is default. Probably a digital one like the ones video cards add now a days. Change the default player to your speakers. Run a sound test.