After upgrading to 10.5.5, I've noticed a something different. 1. OSX hangs more often, maybe 3-4 times this month. Often as in noticeable compared to the past. OSX will freeze the screen but the mouse still moves. I've two freezes that happened when I open Dashboard, and open Finder. The other times I can't remember. 2. My graphics card the 1900XT's fan is behaving strangely. It will revved up on and off and on off, despite me not doing anything intensive. The intervals are not instant though, maybe a few minutes apart. I'm typing this with Firefox opened only and there's one revved up. Is there any utility to check the graphics card? Or maybe it's just a sign that the graphics card is heating up too quickly. The fan kicks in. It cools. Then heats up too quickly again. That's my logic. 3. I've two cases where my LCD just blacked out. Once the Mac restarted by itself as if the power plug was pulled out. The other, the LCD just blacked out and I have to hold the power switch to restart. Overall, my Mac is still working with, I think 99% reliability. But I want to get it back to 99.9%. I'm using the first gen Mac Pro.