Unusual heat and whirring noise

Question

Starting this summer, every so often, my computer will start making a strange sort of whirring noise. It sounds kind of like the noise the hard drive makes when it's spinning, except it's continuous and it doesn't stop or change until I close my computer. Whenever this happens, the computer also gets unusually hot - particularly in the back left corner, around where the AirPort and RAM slots are. I can smell a sort of hot-metal smell if I get close to the computer.
I usually resolve the problem by closing the computer and letting it sit for a while. Generally it cools down in a few minutes and is fine again when I open it.
Thus far, the problem has happened several times while I was playing Snood (a version that's not optimized for Mac and uses a lot of memory), and once while I was watching a video on the New York Times website. I've wondered if the problem was caused by me using too much memory - but the computer doesn't seem to have a problem when I'm using Adobe InDesign, NeoOffice, Microsoft Word, and Mail all at the same time, which I would think would take up much more memory than one video playing on Safari.
Is this just my computer overheating (and if so, how can I fix it/prevent it from happening)? Is something wrong with my hard drive? Or is it something else altogether? Should I be worried?
Note: I bought my computer in the summer of 2004, but the hard drive died in the summer of 2005 and had to be replaced. So my hard drive is a year younger than the rest of my computer.

Answer 1

Welcome to  Discussions,
They can get hot in Summer, but if it ever gets to the point of overheating it will go into a coma until it cools down again.
Having multiple applications open is no great stress, more having one processor intensive game can really heat things up. I remember playing SimCity over a few hot days and my little iBook was the hottest it has ever been. But it still kept running.
The whirring sounds like your fan spinning into high speed. They can be quite noisy compared to normal fan speed.
One tip, if you don't already know it, is to operate the iBook on a flat surface for heat dispersal, and not cradle it in your lap. On a table or a hard floor or surface will absorb some of that heat.
On really hot days, which to me means over 40 degrees C in Australia, I have a fan blowing over the computer. Not practical for a laptop outdoors, but I don't try and push them too hard on those really hot days.