DO NOT FORGET TUBE/HOSE CLAMPS. Make sure you put hose clamps on your hoses that are connected to you waterblock. I'm actually embarresed posting this, but i really hope this will stop atleast one other person from making the same mistake. 300 dollar mistake. owch

I have always been afraid of putting water in my pc. One leak and $1500 down the drain.

Depending if the computer was on or off when the pump turned on, that can tell you if the motherboard can be saved.

I have been given some dirty motherboards, and I do clean them with a water hose to make them perfectly clean (where an air compressor wouldn't even help). Just let it dry, and all is good. (and when a ZIF is concerned, aid it with a hairdryer to get the hard to dry spots).

Never had a problem..

It was turned on.... could that mean its easy toast ?

it could. there was current running through it..

water kills electronics, ONLY when an electric current is running through it..

let it dry, and use a powersupply you don't care for (you might short it out if the mobo is dead), and try.

If you buy a quality water cooling kit, odds of a leak are incredibly slim. The water pressure is really low.

Problem is, there are a lot of cheap/crappy kits out there.
A bigger problem is pumps failing and not getting any circulation and parts overheating. (Although newer hardware should shutdown when this happens.)