All Dell computers are PC computers, whether they're a laptop or netbook, or a desktop computer.
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Power failure events can produce power spikes or power surges that can damage the computer or anything connected to it - that damage can happen even when the computer wasn't running, if it was plugged into AC at the time. Probably most frequently, the power supply and/or the mboard has been damaged on a desktop computer, the mboard has been damaged on a laptop or netbook computer, and usually there's nothing wrong with the ram or the drives, although if the computer was running at the time, data may have been damaged on the hard drive(s).
You can't rule out the power supply on a desktop computer having been damaged until you've tried another known good power supply with your system. If you can borrow a power supply from another working fine system, try connecting that to your system.
If a known good power supply connected to your system produces the same video resullts, then it sounds like your mboard is damaged if you're using the video adapter built into it, and/or if this is a desktop computer and your monitor is connected to a video card installed in a mboard slot, the card either has developed a poor connection in it's slot, which sometimes happens from the effects of a power failure event(remove the AC power to the case and try removing the video card and re-seating it), or the video card is damaged.