If you bought the computer as a pre-built, then most likely, the company used a very low quality PSU to improve their profit margin.
I don't think a day goes by here on Tom's that we don't see a low quality PSU fail and we are left trying to figure out whether it killed the motherboard, CPU, GPU, all of the above, none of the above, etc.
The low quality models use thin gauge wiring, poor Chinese-made capacitors and don't have good fault protection circuits (to prevent damage to computer components when it dies).