Why is my desktop PC running slow?
This is the single most common cause of a slow PC, and most people have no idea it's happening. Every time you install software, there's a reasonable chance it has added...
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PC won’t turn on
The steps below focus on the first two - where the PC itself isn't coming to life. If you're getting power and fans but the screen is blank, the issue is more likely the monitor, the display cable, or a graphics card problem.