When I encode HD video in handbrake, my CPU and Exhaust fans almost max out (at 2200+ rpm from what I saw on iStatMenus). I know it's perfectly normal that they run fast with that type of tasks, I just wonder if I'm still safe at these speeds. It makes a lot of noise of course. Temps seem fine. I've used handbrake for years and it's the first time I've noticed the fans going that high - maybe I was just not paying attention but I tend to remember the CPU/Exhaust fans ran at about 1400-1500 with handbrake before, and that noise is distracting. But more importantly I don't want my trusty mac pro to overheat fwiw, I just updated to 10.9.3 (running Mavericks on this 1,1 without any trouble whatsoever), and the only "upgrade" I made recently is changing my monitor configuration by installing 2 monitors to my Radeon HD 5770 (minidisplay to HDMI) tx.