Buying PC components at a store like Best Buy or Micro Center is easy. You pick what you want and take it to the register. You'll usually have the option to purchase a warranty, or at least to take things back within a return window if they quickly stop working. But buying new parts is expensive, and if you don't strictly need the latest and greatest, it's compelling to seek out used parts. Reusing computer parts is not only cheaper, it can reduce the environmental and labor impacts of PC building too.

However, with the secondhand market comes a lack of guarantee about what you're getting. Unscrupulous sellers may misrepresent parts, and even a trustworthy individual may not have the knowledge to correctly identify the parts or their conditions. That doesn't mean you should necessarily avoid buying second hand PC parts, but it does mean you should educate yourself on how to do so safely and confidently. Here are some of the main things to look out for when buying used computer parts, including which ones to avoid entirely.