"Plastic parts of older computers become yellow or brown over time, so you end up with a computer that looks yellow or brown instead of white or gray. In this tutorial, we will show you how to restore old plastic parts to their original color by using a homemade peroxide-based solution called Retr0bright."
Any major computer upgrade generally requires a full software reinstall too. No so if you heed the advice in the guide to Upgrading a Motherboard without Reinstalling. PCSTATS Tips