The vacuuming, brushwork, and multiple shots of canned air should remove most of the dust and other debris in your PC. Use a microfiber cloth to wipe away any particularly stubborn dust. Never use paper towels to wipe anything down inside a system, because they tend to leave lots of small fibers and dust on textured surfaces. A microfiber cloth leaves nothing behind.
One last tip: If your PC is more than six months old, it's worth reapplying the thermal paste. The thermal interface material (or TIM) used between CPUs and GPUs and their heatsinks breaks down over time and becomes less effective at conducting heat away from your PC's components. To replace the TIM, carefully remove the heatsink and clean any old TIM from the heatsink's base and from the surface of the chip it was mounted to using isopropyl alcohol (or any other alcohol-based cleaner that won't leave any residue). Once the surfaces are clean, apply the new TIM and remount the heatsink. For detailed instructions on how to apply thermal interface material and how to install heastinks on both AMD and Intel processors, check out our guide to installing a CPU cooler.
Regular cleaning pays off
Cleaning all of the muck and dirt out of a system can be pretty gross, at least the first time around, but doing it regularly ensures optimal cooling performance and stability. There's really no downside other than the time spent, which won't be fun if you've neglected your rig for an extended period of time. So get in there and get your hands dirty--your PC deserves a little TLC.
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