"insaneboy" is truly a proper name indeed! 
Your caps have partly "failed" and you just don't know it. More specifically, I assure you that the capacitance level of most of your fluid filled caps is considerably diminished as compared with what they once were when new. And just because your machine powers on as normal does not mean the caps are still at full capacity. It merely means they have enough capacity left so you don't know they are about to fail completely. With it now being 2011 and considering the age of some of these old Macs, I consider it almost dangerous to continue using a machine as normal with the original caps simply because it "appears" to be working fine. Chances are the caps are leaking and you just don't know it, and you will refuse to replace the caps simply because you perceive the machine to be working fine. That's the "danger" I speak of. But you don't have to let "insanity" overtake you. You really can remove the old caps, clean the board, and replace them with tantalums (in most cases).
Unknown_K, who here on this site used Tantalums that blew up? And when did this occur? And what voltage capacity and size of the tants were used?
Tants will blow with over-voltage, so I must assume that whomever used them did not use a properly rated cap?
Your caps have partly "failed" and you just don't know it. More specifically, I assure you that the capacitance level of most of your fluid filled caps is considerably diminished as compared with what they once were when new. And just because your machine powers on as normal does not mean the caps are still at full capacity. It merely means they have enough capacity left so you don't know they are about to fail completely. With it now being 2011 and considering the age of some of these old Macs, I consider it almost dangerous to continue using a machine as normal with the original caps simply because it "appears" to be working fine. Chances are the caps are leaking and you just don't know it, and you will refuse to replace the caps simply because you perceive the machine to be working fine. That's the "danger" I speak of. But you don't have to let "insanity" overtake you. You really can remove the old caps, clean the board, and replace them with tantalums (in most cases).
Unknown_K, who here on this site used Tantalums that blew up? And when did this occur? And what voltage capacity and size of the tants were used?
Tants will blow with over-voltage, so I must assume that whomever used them did not use a properly rated cap?