PSU faulty, or something else?

Yozer34

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Aug 10, 2011
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I've been having a really annoying problem lately: my computer suddenly and spontaneously shuts down, keeps off for 2 or 3 seconds, then turns itself back on again. I've narrowed down the list of possible sources of this problem: (Just so you know, I did not add any components for the past 2 months, and this problem occurred just recently)

So, first of all, I did a (quick) format on my main drive, and reinstalled Windows. The first time I turned the computer on after that, the problem (the computer resetting) occurred within five minutes of regular (not demanding) use. So now, I can conclude that overheating is not a problem, and that the problem lies in the hardware, and not the software.

I'm assuming the problem is from the PSU itself, because the first time this problem happened, something unusual occured as well: when I pressed the power button to turn the computer on, the room's light bulb flicked once for a split second, and this kept happening from then on every single time I turned my PC on.
Should I RMA the PSU, or would the source be elsewhere? What do you guys think?