If I keep getting a "sick" or "dead" GPU, but the others work fine, is that indicative of having too high intensity for SPR mining? Or can it be anything? I seem to be getting it at least once per day.
Usually it's exactly that. Another possibility is that your overclock is not stable. If lowering difficulty doesn't fix your problem you should try adding +6 mV to voltage or subtracting -10 MHz from the core clock.