Here's how to think about your fans.

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When you're building or upgrading a PC, chances are you're thinking more about how to improve your machine's performance than you are about where you're going to put the fans. Improving airflow might not be as exciting as adding a new graphics card, but it's essential to getting the most out of your rig. Fortunately, there are a few simple principles you can apply to any PC build to keep all your components running cool .

It's important to understand exactly what you're trying to accomplish when improving your PC's airflow. PC components generate heat as they run, which gets trapped in the case, degrading system performance if things get too hot. The point of fans is to draw cooler air from outside the case over those components and exhaust the hot air they generate outside.…