Re: Are you sure?
First time building a pc.
Fitting an ATX P1 mobo into an old AT case; not all of the holes and riser lined up of course, so I used lego to insulate.
Finish plugging everything in, or so i thought, and turned it on, happy to see the bios flash up.
Then - ERROR: no FDD detected
Realise I missed the power plug on the FDD, and rush to plug it in, forgetting to power off first. Managed to misalign the holes and start to slide it in one pin over where it should have been (somehow the slots and notches didn't prevent this). BZZT-CRACK! Flash! PC power dies. Strange whine.
In shame, turn off, unplug. Align and insert correctly. Expecting nothing, I turned it back on. Whirr, Beep! All is fine!
That's when I learned this PSU had a circuit breaker instead of a fuse (or worse, soldered in fuse; blew a few of those with the 115v switch in the wrong place in my time).
Lesson learned; Measure twice, cut once. And they don't make 'em like they used to.