POP! What was that???

I was sitting in my office yesterday afternoon, with Rosie, our Australian Shepherd, asleep at my feet, when I heard a loud POP! It sounded like a fire cracker. Rosie didn't budge, which is no longer surprising as she has been losing her hearing lately. I looked around to see if I could find something amiss. Nothing. No smoke. No funny smells. No new holes in the window. Nothing. So I went about my work as usual.
Today, when I went into the office and sat down to read the morning's e-mail, my monitors were all goofed up. Argv! This looks like what I would expect from failed hardware: gobbledegook on the screen. So I pulled the video card and the problem is self-evident.

The tops of three capacitors were blown off! I'm not really surprised the capacitors blew -- that happens on these cheap devices. What surprised me is that I worked well into the evening yesterday with no problems. I presume that when I retired for the evening and the screenblank kicked in, that was the end of proper functioning. Fortunately, I also have plenty of spares hanging around... always be prepared for failures.