Have been having the same issues as well with my EVGa 970.

- Happens in FULL SCREEN games only; windowed games are completely fine (I run EVE and FFXIV windowed, I can run them 8 hours easy without a hitch -- both on max/ultra graphics [EVE can even go into 1k+ player battles without problems too])
- Problem happens even if I lower game graphics to minimal.
- Card not overheating, have graphs to prove it.
- I do see it spike 100% GPU. Not all the time. Most of the time GPU bounces from 60-80% during huge fights in PlanetSide 2, then it hits 100% and stays up there for a bit.
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- Screen flickers and displays "No Signal" after 30min -> an hour.
- PC Still is on, and I can type / message / voice chat people in the full screen games no issues
- Installed Afterburner. Under-clocked, over-clocked, upped the fan speed to 100
- Clean/Safe-mode uninstalled drivers and re-installed (and have tried every driver on their site multiple times). Most drivers won't fix the issue, there are two that did for a couple of days then the issue came back.
- Bios update did nothing
 
Trying to figure out what to do next. Don't think I can RMA as I bought the card off of Amazon. Is this a manufacturer issue or a driver issue? I don't want to upgrade to say a Titan just to have the same issue happen.

Should have expanded on that. I didn't register the product within the 90 day period. -KR have a 3 year warranty I believe only if you register within that time frame (according to their website). So for now need to figure another route.

It's not the video card.
I had my 970 for a long time while I was still on windows 7 and NEVER had an issue. I upgraded to windows 10 and that's when hell began. I would constantly get driver crashes...eventually the crashes went away and now i'll randomly get a black screen while playing CSGO (the issue happens ONLY in csgo). This is an nvidia driver issue, not your card. I've done a clean install / tested in a new rig...same issue.
 
Just funny that the entire year I had the 970 while using windows 7 I had zero issues lol.

I recently struggled with the same issues most are having here. Screen would flash black several times after playing for Dark Souls III or TF2 for 30+ minutes. Before I tried to RMA, I decided to give PricisionX16 a shot to adjust the fan curve. After cranking up the fan curve to hit 50% around 40C I have yet to have the black screen issues. I have a pretty airflow-friendly case but it is very possible that the OC on this card simply generates far too much heat without adequate fan compensation to run for longer periods of time. Hope this helps the rest of you.