Get a battery backup. Even a small one will prevent voltage fluctuations from affecting your PC. A larger PSU with more capacitance may help, but a battery backup is definitely going to negate the problem.
Good thinking.
If a UPS does not solve this, it may be some sort of radio-frequency-like interference.
Also check the fan on your GPU and make sure it is spinning. Whenever I played a game my computer would crash, turned out the fan was dead on the GPU and causing it to overheat.
What RichardCMongler said...it's a voltage jump. Get a UPS:
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