To inaugurate my new position here, I'm Kayin, I've been in PCs for the past decade and change, started water cooling on a Slot A Athlon with a cross-drilled copper slab, a pond pump and a heater core. The craft has moved on since then, and so have I. I'm writing this series of articles to explain what I've learned, especially from my engineering/materials science studies and how it applies to our field. This is the first article of at least a seven-article series, on the nuts and bolts science of PC cooling.