.
[/quote]

70% should be okay

set clocks

to

tdp 70%
core +10
ram + 100
fan 75%

see how that works

[/quote]

I use these parameters, except have the fan on auto. It looked like it was running at about 57%. Fired up five of the cards yesterday at 10:30 AM and ran stable until I went to bed at 10 PM. However, sometime in the night it stopped again. I am mining zcash and using the EWBF CUDA Zcash Miner. In the mining apps window it was continuously trying to restart. I close the window, and tried to restart the minor but it would only flash for a split second and disappear. When I restarted the rig, I pulled up MSI afterburner and all my settings were gone again. So after resetting, I have fired up the five cards again with the  fans set at 75%.

Is it okay for the cards to run the fans at 75% for a long period of time?

Not sure where to go from here. I have tried reinstalling the miner software as well as a refresh copy of Windows 10. Could it still be a hardware issue, even though it ran for so long? still haven't tried another PSU on it.