I'm looking for some help in figuring out whats causing these crashes. Its started a few months ago while I was playing dead by daylight so I dropped the graphic setting to medium from ultra and this fixed the issue, then I had a crash with guardians of orion, so again I dropped the graphics to solve the issue, then I crashed playing day z, I haven't played day z again as I need the graphics to be set high as you need to see whats going on.
 
My system specs are
 
i7-4790k 4gig
16gig corsair ram
GTX 970 4gig
asus Z97-PRO
EVGA super nova 850 gold
1 x 120 gig SSD
2 x 1 TB WD black HDD
 
 

I installed MSI and set both the core and memory clocks to the lowest they would go, Played day z for about an hour before it crashed loaded guardians of orion and it crashed within a minute of loading in, I have a picture of what MSI was reading during the last play session but I don't know how to attach pictures to this post.

In addition to the above, anytime I see 'ASUS' and 'Crashing' used in the same post, I think AI Suite..I would remove it if you have it installed, at least for the time being..You should also revert any overclocking, uninstall the NVIDIA drivers and optional driver components (esp. GeForce Experience) with Display Driver Uninstaller (DDU) and install the latest NVIDIA driver using the Custom (Advanced) option to install only PhysX System Software along with the Graphics Driver..If you have games 'optimized' with GeForce Experience, 'revert' them before running DDU..Your card may be getting hot, try forcing the GTX 970 fan/s to 100% with Afterburner or Precision to see if that matters and check on the CPU temperature too.
 
After removing AI Suite, you should run AI Suite Cleaner to remove the leftovers..I have AI Suite II and III cleaners and a Readme here on my OneDrive page.
 
You forgot to say what OS you're running.

If I may add, what is your GPU temp when it goes black?  I have been folding on my replacement 970 and I've had to manually crank the fan to 70% to prevent the system from overheating and having the screen go black after about 30 minutes or so of folding as the default fan curve wasn't kicking in fast enough.  It sucks as the computer sounds like a jet engine, but I don't want to RMA the card again as I paid for advanced RMA and the exchange rate killed me when I got refunded on my Visa..I lost 40 dollars as the dollar was worth less when I paid for the advanced exhange :(.

77c isn't an issue.