First off, here's the hardware we're dealing with: Al Powerbook G4 (1.25) (768 MB RAM), Panther 10.3.1. I've recently discovered the Processor Performance setting under Energy Saver in the System Preferences. Panther set my computer to the 'Automatic' setting by default, so I decided to give the 'Highest' setting a whirl: my, what a difference it makes. Expose, minimizing/maximizing windows, and just about everything else in general now runs much smoother. However, making this change has brought a few other issues to the forefront. Namely, I've noticed that my PB constantly emits very faint whining/buzzing sounds. Before I switched to 'Highest' Processor Performance, I used to notice these sounds occasionally (e.g., when using expose), but still very rarely -- now I hear them all the time. Usually, it's very difficult to hear these noises -- you either have to be in a silent room, or stick your ears right next to your keyboard and listen very, very closely. Certain things really set the noises off, though: for example, running Dreamweaver MX 2004 and waving the mouse cursor around while an MX window is active will really get the thing going (strangely enough). I've done some research into the issue, and I noticed that several postings have already been made here... http://forums.macrumors.com/showthr...rpage=25&highlight=strange noise&pagenumber=1 ... as well as some extensive coverage of the same issue that's affecting G5 owners ... http://www.xlr8yourmac.com/G5/G5_noise_tips.html Disabling 'Nap' mode using the CHUD tools does indeed put an end to the noises, but I've noticed that it also results in higher CPU temperatures: the CPU temp in my PB jumps up about 20 degrees (F) when I disable Nap mode from 120 degrees to 140-145. This, in turn, causes the internal fan to kick in more often, which isn't the quietest thing ever. Circumventing this feature of the processor doesn't seem like a particularly healthy thing to do, either. I think I can deal with the bizarre noises (especially with a good pair of speakers or headphones on), but I was wondering if any of you had found another way around this curious issue. Reverting back to 'Automatic' processor management would also work, but then I end up taking the speed hit. Sorry for reviving the topic, this is just something that's been bothering me all day. Please post any helpful insights you might have.