Hi! I'm thinking about replacing the Radeon 4870 in my mac pro 4,1 with a Radeon 5870. Can anybody tell me about the 5870's fan noise compared to the 4870? What bothers me a bit with the 4870 is that while it's not particularly loud, it catches your attention by always spinning up for a moment with every little action you take, like scrolling in Safari. How is the 5870 in comparison? Thanks for your input!