Just because the temperature is fine doesn't mean its stable. Try bumping up the voltage slightly or just settle with a lower clock speed.
But I can run Unigine for 40 minutes on Extreme with 0 issues and play BF3 on ultra at 60 fps stable for 3 hours without going over 70% (usually 60%) load and not encountering any issues. Smite is a very easy game to run even on highest settings, why is this happening?
Could the issue be with a bad motherboard? I'm using a B75M...