I've been using the ASUS ROG Z690 Formula motherboard in all my recent CPU water block reviews, and also detailed it here for a specific EK VRM bridge block article. While the board has reached end-of-life status at ASUS internally, the company's customers are only just starting to face problems. The board's unique selling point is that it comes with an optional CrossChill EK III hybrid VRM thermal solution, which is effectively a waterblock for your VRMs to keep them cool at all times. Based on ASUS's official advertisement of "nickel-plated" and EK's involvement, everybody assumed that the material used is nickel-plated copper, but it turns out it's something different, most probably nickel-plated aluminium.

This is not the first time that ASUS has failed the material mix in their watercooling products. The first generation ROG Formula motherboard VRM blocks used plated-aluminium that introduced corrosion when added to a watercooling loop that has copper/brass/steel components elsewhere. Mixing metals in a watercooling loop is a bad idea and will result in galvanic corrosion from the different electrochemical potential of the metals. This can result in the block etching off and flakes/chunks getting in the loop to create an increasingly worse reaction with the coolant used. This can lead to blocked channels and even pump failure due to the corroded materials jamming the impeller.