I would go with a 2nd RMA after checking the following:
- Making sure you're not overheating. What are the temps prior to your GPU crashing? Have it showing through the game via PX1. If crashes continue to happen, lower the GPU temp target and see if that gives you stability.
- Have another PSU to test it out with?
- Check the CPU socket and CPU itself for any bent pins.
- Any CPU/RAM OCs? If so, run it all at default.
- If memtest passed, than your RAM is fine.
- Running any backup power to the PC? If so, disconnect it.
What's confusing is the fact that you're running GPU and system benchmarks just fine which makes this whole thing odd. It could be game related with the hardware combo that you have. Are there any other game titles you could test this with?
If the issue still persists, I would than go for the 2nd RMA.
- I've monitored temps through Precision X1, as well as HWMonitor and GPU-Z. All show 60-high 60's during very intensive load (i.e. COD Warzone). Every other game has run cooler, so I do not believe overheating is the cause.
- I've tested the first GPU on my original PSU (Corsair CX500, which was already in use in my system and I just upgrade specific parts). Had the issue so I upgraded to EVGA 850 GQ early on into the first GPU and issue still occurred. I have not tested it on any other GPU besides the current 850 GQ on the 2nd RMA'd card though, and I do not have any other PSU lying around besides the CX500 which was upgraded because of wattage limitations that was causing this issue. Knowing this, would you recommend I still proceed with a 2nd RMA and hope 3rd time is the charm?
- Default CPU/RAM. Was upgraded when I upgraded to the first GPU. Issue occurred pre HD partition, and after.
- Glad RAM is ruled out, I was concerned it would be left to my RAM/CPU/Mobo if GPU isn't the problem.
- No backup power.
I, as well as other friends who builds their own PCs, were all pretty confused as well. It would happen on almost every game I played (CS:GO and COD Warzone). I tested it on Divison II as well since I knew that game was pretty intensive and would crash fast and it did crash there. One game I tried that did not crash was Warcraft 3: Reforged playing custom games/Bloons TD (pretty non-intensive games). I'm not sure if the intensity of the game necessarily matters or not, though CS:GO itself is not all that intensive, so I've been left stumped.