Couple ideas... about why its failed twice now... but pretty speculative...
1) Maybe your mobo fan header sometimes overvolts the thing, and the extra current is too much for the microcontroller so it pops. a dumb device wouldn't care so much about a little more juice (it'd just spin a little faster while overvolted).
2) Did you replace the fans that came with the h100 with different more powerful and power consuming fans? If so, plausible that the extra current they'd suck up could exceed what the circuitry in the h100 can deal with.
3) You say it happens after moving or reconfig'ing things, on first power up after that. Maybe the psu and mobo are not fully grounded to one another (or the outside world) until that first power up, and there's a spike in the 12v line large enough to damage the circuity. And since typically, a dumb device would be on that particular header, the mobo doesn't go out of its way to regulate that signal.
This has happened on 2 different motherboards. It's just getting expensive replacing them. I don't have time to wait weeks for an rma every time I disconnect it, unfortunately. I will rma this one, but I'm not risking that feeling of panic as I get that ozone smell again.
The molex connector on them is horrid, too. There just doesn't seem to be a lot of quality control on them. Is the h100i better in this regard?
It doesn't happen on the intial installation. If I disconnect everything and reconnect it, it happens. The first time, it was never disconnected from the power supply. I just swapped the motherboard. The only thing that was disconnected was the fan header and water block.
This time, I replaced everything. It's really hard to make a mistake hooking it up. Just plug in the molex and fan header.Edited by Droogie - 4/20/13 at 1:17am