I don't think it's the "white matter" that caused it to explode, I figure your water block leaked, the stuff reacted with your warm components or evaporated and left behind that residue.
^-a leaked H60 leaving white residue behind
Contact CoolIT, they should hopefully reimburse you for your components. Be sure to take lots of timestamped pictures as evidence!
That said, as rare as these leaks are it's anecdotes like these that make me stick with traditional air coolingEdited by mingqi53 - 4/4/12 at 2:35pm