Try testing each card individually with the other completely removed from the system.

Yeah when I get home from work I will get that done. May just rebuild the thing from scratch and check each card. It really is getting annoying.

uncle poop
So as a lot of you know I have been having a lot of issues these past four months with my computer. I finally got things put together and seemingly working with each other. I went to play some Rocket League and my computer freaks out just as the main screen for the game pops up. By freaks out, one sound will skip fast constantly, so a button press sound will continually play but as quick skipping. Like if the sound is beep when the computer freaks the sound goes bebebebebebebebebebebebe. I know great description me.
 
My monitors will usually go white or a white and pink colour and I will hear the windows exclamation sound play. I then have to turn off my computer and restart it. At first I thought this was just Rocket League and Steam but I have tried the other game I have Diablo 3 on Battlenet and although I actually got to play the game for a few minutes I got the same computer freak out. I have never experienced a crash like this with any computer I have ever had so this is new to me. Could this be a sound issue? I am only using the on board sound and not an add on one. I have removed the game launchers and two games I have and reinstalled them and still the same results. If only I could afford to replace this whole system already, too many headaches recently this this old dog.
 
System specs:
Intel i7-2600k
16gb Ripjaws
Asus P8Z68-v le (swapped out for a bad EVGA Z68 board 3 days ago)
2x EVGA GTX 560ti (not in sli as this motherboard does not support it)
Windows 7 Pro 64bit 

I had a similar problem with my PC last year.
Had similar system as you at the time, except i was running a gtx 970.
Media based applications would cause my pc to lock up or crash with similar sounds you are describing.
 
I tested everything the same as what you have done, and what others have mentioned to do.
It was some part of the onboard audio controller that was bad on the mobo causing the problems. (had ASUS Z-68)
 
Found another mobo z68 based gigabyte i believe... and everything worked as it was supposed to.
Im not saying its your mobo, but i had read other forum posts about ASUS Z68 boards having similar problems.
Good luck with your testing, hope you get it fixed, and let us know the outcome.

Well I retested the gpu's and it turns out one of them is actually bad. I had tested them, it was really the first thing I did. Anyway, I figured out my problem, now I have to see if I can find a really cheap evga gtx 560 ti somewhere. Although thinking about it rocket league can run on just the one so really it doesn't matter if I find another one.
 
Thank you all for you help and sorry about my stupidity. Funny how something can work fine during a test or something then not work the next. Luckily I finally found it though.