Need some advices: GeForce GTX 780 is probably damaged

Hello guys,
I need some advices what I should do or try to get one or both of my GTX 780's with reference cooler working fine again...
Here's my problem: Yesterday I played GTA Online Power Play and at the end suddenly there was green flicker all over my screen. But it was only in GTA V, otherwise at my desktop there aren't any signs of damaged hardware. I recorded it and took one screenshot with my smartphone, because it might help to solve the problem. My other system specs are in my signature. I have SLI enabled and the latest Nvidia drivers installed (v. 368.39). The temperatures on my first 780 are at about 81C° when gaming, the second at about 70C°. I tried the latest FurMark stresstest and both of them passed, maximum temperature was 85C°. Of course I searched in some forums someone who had the same problem like me, but unfortunately there wasn't someone. Some folks with sort of similar problems got told that the VRAM could be faulty. Some said that it would worth a try to bake the GPU but I don't have no right clue to do this because of the missing knowledge with which temparatures and time I should bake a GTX 780 with reference PCB . The "master GPU" (that one which is plugged in the first PCI-E 3.0 slot on the mainboard and is connected with my monitor) is a EVGA Superclocked and I think I still have warranty for it. The other GPU, I purchased over eBay "Kleinanzeigen" without original packaging. The seller said it was unused and he couldn't tell me from which manufacturer (maybe Zotac) it was. When I got the card, I looked upon it and there weren't any signs of use (like dust, scratches etc.). So on the second card I have no warranty at all. I think the 780 from EVGA is responsible for the flickering, but I am not sure.

I made the thread because maybe someone knows a solution without having spending time and effort into sending the card to an EVGA service.

 

Yeah sure, I will do that soon. After I did it, I will update the thread