I have a question about Liquid cooling PC's?

When distilled water leaks, it will come incontact with dust and other metals that will make it conductive, not to mention the copper block inside the loop will do the same. The corsair H50 is a closed loop and the story's I have heard of it leaking are few and far, the ones that do corsair replaces the whole system free of charge. The HD 5970 runs really cool, cooler then the HD 5870 which is half the power of a 5970, it runs so cool because of the vapor chamber cooler design(should get no more then 80c max with it overclocked)