My Quad-Core Mac Pro tower is two days old. Initially, I was impressed with how quiet it was compared to my older Macbook Pro. Then on day two, for some reason it started running very loudly. It's not just a "little" loud- my wife walked into the room and asked what the noise was.

At first I thought this was just because I was hitting the CPU a bit (importing my iPhone library into iLife '09, and running Eclipse). But now that that's done, Activity Monitor shows a virtually idle CPU; there's nothing running that ought to be causing this, as far as I can tell.

I tried powering it off & letting it cool down for a few minutes to no avail; about 10 seconds after powering up, the box gets loud again. I took a look at it with the side cover off, and it seems to be the fan near the top middle, between the power supply and the disk drive.

It can't be a dust issue, as the machine is only 2 days old (and I peeked inside anyway just to be sure- clean). I did do a software update over the past 24 hours or so, but I can't say that it occurred immediately after that. I also did a migration of my old apps and data from my MBPro, for what it's worth.

1. Why is it suddenly so loud?
2. How can I monitor the fan speed and various system temperatures?

Here's a link to my temps and fan speeds.

UPDATE 1:

Took it to the Apple Store. They took it in the back (where it's presumably quieter) and ran a fan diagnostic; no problems were found. The guy also told me that it was "a little loud", but normal. I don't buy it. It was virtually silent the first 24 hours I was using it. They would not replace/service it in the store (grrr... that's why I went there, as directed by Apple Care) but said I could get a replacement from the online store, as it was just purchased. I think I will try that.

UPDATE 2:

Apple is letting me send it back for a replacement. Glad to see so many responses to this question mentioning that the MacPros are usually silent; it's not all just in my head. :-)