Now that your done with the radiator we can move onto the waterblocks. Thankfully the waterlbocks are much easier to clean than the radiator. The first thing to do is to take the waterblock apart, and flush it with deionzied or distilled water. After you have flushed all of the parts, grab some vinegar and pour it into a glass or ceramic bowl. Plastics wont do as they can actually stain the waterblock. Once the bowl has been prepared, place ONLY the copper base of the waterblock in the bowl, making sure it is fully submerged and that only a small portion of it (non wetted surface) is touching the bowl. Set the baseplate stand in the vinegar from anywhere between 8-24 hours. Upon removal of the waterblock, flush it with disilled water and then lightly scrub it with a NEW toothbrush that has been cleaned off with rubbing alcohol and distilled water.