Computer adventures!

So I've got a story; sit around the campfire and I'll show you the mystical wonders of my day a couple weeks ago.

It all started when my friend needed some computer help; he was hosting a LAN party and needed extra computers. He also had a pile of proclaimed "dead" motherboards with Pentium IVs/Celerons in them. I went over to his house to see if I could get any of them working. Our best bet motherboard had a "case open" warning that wouldn't allow the computer to continue booting after the POST screen. Here's the fun part.

I think "How hard can it be to find the jumper for the case open warning?" Then I start poking around. By my highly sophisticated procedure (read: shorting pins with a screwdriver to check different configurations) I was able to find out what made the system hang. There was one pin configuration I couldn't try, however; the security jumpers were three horizontal pins; I needed to jump the first and the third.

I grab a standard three pin connector with a wire on each end, strip and twist. Here's the lucky part; I didn't use a screwdriver. After inserting the jumper and hitting the power button, nothing happened. The fans spun up but the computer didn't POST. Now my little brother, who was sitting nearby, announced "HOLY SH*T THERE'S A FIRE!" I had accidentally jumped the power line to ground and my twisted wires had started glowing white hot. A quick power disconnect and a hasty carry outside to let it vent ended the insane part.

The computer does still boot; I do not know how, so we refer to the motherboard as "JesusComp."

My friend is keeping the homemade jumper as a testament to the time that I actually got something wrong.

As for the practical part, why didn't the internal breaker in the PSU trip? It's a fairly new PSU -- has the ATX 4-pin connector and all.