No sound gaming in 4k on Sony XBR x850b with gtx 780 ti

[Panzer AppleHusky]

So I'm at a loss.
I recently purchased a 4k tv in hopes of being able to game at that resolution. For some games, it's great. The GTX 780 ti performs quite well at such a high resolution. The problem I'm having is that with some games like Borderlands pre sequal, I cannot get any sound out of my system while running in 4k. This only happens with select games and only when I'm in the game. When running the desktop at 4k, it's fine, but as soon as I start a game up, it goes away.
This is my setup
CPU: Core i5 4670k
MoBo: Asrock h87m itx
GPU: MSI Geforce GTX 780 ti gaming edition
RAM: 8gigs

I have the computer connected via hdmi to a sony 4k receiver which is then connected to one of the tv's hdmi ports.

So if any one of you guys or gals have a setup like this, a problem like this, or have any advice, tips or tricks, I'm all ears cause I'm absolutely stumped.

 

[-Lone-]

So I'm at a loss.
I recently purchased a 4k tv in hopes of being able to game at that resolution. For some games, it's great. The GTX 780 ti performs quite well at such a high resolution. The problem I'm having is that with some games like Borderlands pre sequal, I cannot get any sound out of my system while running in 4k. This only happens with select games and only when I'm in the game. When running the desktop at 4k, it's fine, but as soon as I start a game up, it goes away.
This is my setup
CPU: Core i5 4670k
MoBo: Asrock h87m itx
GPU: MSI Geforce GTX 780 ti gaming edition
RAM: 8gigs

I have the computer connected via hdmi to a sony 4k receiver which is then connected to one of the tv's hdmi ports.

So if any one of you guys or gals have a setup like this, a problem like this, or have any advice, tips or tricks, I'm all ears cause I'm absolutely stumped.

Why not just connect the HDMI cable directly to the TV? Also, where does your sound come from? Surround sound that's plugged to your pc or sound from the TV?