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.Multiple reports on watercooling communities have come out over the past couple of months about the VRM block in the ASUS Z690 Formula displaying clear signs of corrosion. Months went by without any official statement from either ASUS or EK and it took until ~10 days ago that a more popular such post finally got enough traction to make progress with the issue. Earlier today, EK sent out an email to those customers who purchased the VRM Bridge for the motherboard, to finally acknowledge the use of mixed metals in the VRM block. This revelation makes the block incompatible with any copper-based CPU block and even the very VRM bridge linking the two. EK has not yet mentioned how this could have slipped past the brand's attention until this point, given the company's logo is on the VRM block, but frankly ASUS merits more focus for not bothering to tell any of the undoubtedly thousands of customers who purchased the Z690 Formula motherboard, in addition to all the media partners who have been using it too. As it stands, EK suggests reaching out to your local ASUS support team for a working replacement, but so far it sure feels like this issue is being handled quietly to not get the word out as much as possible. If you are using this motherboard with the VRM waterblock, then my recommendation is to flush and clean the entire loop, replace the coolant, and remove the VRM block from your loop for the time being as the VRMs can still be air-cooled.

Here's the full contents of the EK email, provided to us by an affected TPU reader.

EK-Quantum Momentum² VRM Bridge ROG Incompatibility Announcement

Dear and valued EK Customer,

We regret to inform you that the ASUS ROG MAXIMUS Z690 FORMULA motherboard is incompatible with our EK-Quantum Momentum² VRM Bridge ROG Maximus Z690 Formula solution, as well as other copper-based EK products.

We have developed the liquid distribution VRM Bridge solution to help our users get the full benefits from motherboards that feature CrossChill EK III hybrid VRM thermal solution by connecting any EK-Quantum Velocity² CPU water block directly to the VRM thermal water ports.

Unfortunately, EK and ASUS have discovered the issue of the VRM block corrosion. We are already working closely to address this issue and offer support to all affected customers.

ASUS is readying an adequate replacement hybrid VRM thermal solution for everyone affected by this issue. Feel free to reach out to your local ASUS support team for any additional information.

In the meantime, EK and ASUS are improving collaborative processes and development guardrails to ensure all future products exceed our customers' expectations.

We are genuinely sorry for any inconvenience this might be causing you.

We appreciate your understanding,
Team EK

Update Feb 15th 08:16 UTC:
TPU Forum member Trev shared the following photos of his watercooling setup after running just 10 weeks with the VRM block in the loop.