Please humour my ignorance,
what are the reasons for overclocking?
Increased performance for the same cost. Basically thats it man. People will post with other suggestions but all it boils down to is better performance than the price that you paid.
More, dare I say it, bang for your buck.
If you can spend $20 on better cooling for your CPU and overclock by a couple of hundred megahertz then you will get more performance/throughput than without. For instance one of the most popular overclockable processors in recent memory is the Intel P4 1.6A (A = Northwood core). With the default Intel Heatsink and Fan some of these overclocked to over 2.2Ghz (thats an amazing increase 600Mhz or more. So its like getting a 2.2Ghz P4 for the price of a 1.6Ghz (which at the time was quite a bit less expensive than a 2.2Ghz P4.
I thought finance was the case. I personally wouldn't want to jeapordize my systems stability. I'm just about to build an AMD Athlon XP 2000 system.
Alternatively to gain more performance than is currently available, for example by clocking a top end processor even higher.
And then of course there is the boast factor of ... "My PC is 3.5Ghz...." etc. etc. etc.
The love of labor is another excuse. Some people (like myself) don't need the extra MHz but overclock just because we can. Since I can do it.. might as well.
You won't be if you don't take it too far, and "too far" can be quite a way off usually. A few hundred MHz is easy to gain and still be in reasonable limits for most processors.