Sorry to hear about your issue. In general this could be caused by a number of different problems. I would recommend to reinstall the graphics drivers with the "Clean Install" option enabled after choosing "Custom/Advanced" Install during the installation process after the drivers uncompress. Drivers available here. If there is no change we have seen sometimes where the audio controller on the card for the HDMI port can cause issues. Please try the steps in this FAQ to disable the HD audio.
Next I would recommend setting your memory timings, voltages and frequency manually in the BIOS and then retesting. You would just need to find the recommended settings from the manufacturer and go into the BIOS and set them manually (Typically found under Frequency/Voltage control and Memory Configuration.) Once they are set up I would recommend to run memtest86+ (memtest.org) for a few full passes to ensure the RAM is working properly as the 500 series cards can be very sensitive to correct ram settings.
Next I would check if the PSU is providing consistent power with the card installed. Go into your BIOS and look for the +12v reading, this is typically under 'PC Health Status', System Monitor, Hardware Monitor'. A healthy reading (official ATX spec) is between 11.4 - 12.6v, and stable. However, different brands have different tolerances for overvolting and under volting, if it is outside 11.9v and 12.30v, or if you observe consistent fluctuations of more than .05 volts then this may be a sign of concern for a degraded or failing +12v rail. However, BIOS will only show you an idle reading. You can try monitoring the +12v in Windows under load, using a free program like HWMonitor.
If the PSU is outside of spec or fluctuating, or if the problem persists, would there be any way for you to test the card in another system to see if the problem follows the card, or perhaps any way to test a similar powered card in this system or test with a different PSU?
Then try testing the card with some free diagnostics programs we provide, I would recommend Precision to monitor the temperature of the card and then run a GPU stress test for about 30 minutes with OC Scanner. You will want to "Enable Scanner" and also go in the settings and 'Enable On Screen Info", then Validate Changes and "Start GPU Stress Test". Please let us know if this reports any artifacts/crashes/errors and the max temperature reached under load.
Regards,
EVGA Tech Support