Conclusion
There is no such thing as a jack-of-all-trades that excels in every discipline. Our testing of Asus' ROG Poseidon GeForce GTX 1080 Ti 11GB Platinum Edition makes this point clear. The card doesn't have any serious flaws, nor does it do anything explicitly wrong. Yet, it doesn't achieve top scores under air or water cooling. Simply, this is the result of compromises made to give the ROG Poseidon its flexible hybrid cooling solution.
The card's saving graces are, first, its aggressive factory overclock, and second, the ability to easily switch from air to liquid cooling without voiding Asus' warranty.
And how about its weak points? As soon as the card is installed horizontally in a closed case, the air cooler's slight deficits compared to competing solutions start to show. The ROG Poseidon GeForce GTX 1080 Ti may even sit at a disadvantage to Asus' own ROG Strix GeForce GTX 1080 Ti when it comes to air-cooled performance. Even though the ROG Poseidon isn't particularly loud or hot, there is room for improvement.
The same conclusion applies when you switch over to water-cooling. Obviously, a small, U-shaped heat pipe doesn't stand a chance against a proper water block with micro-channels. Furthermore, we noticed that flow through the pipe was almost halved compared to more purpose-built solutions. While this is still acceptable, it doesn't earn the ROG Poseidon any victories.
In the end, though, Asus set out to enable a simple solution, perhaps for folks uncomfortable with the idea of installing their own water block. To that end, the company succeeded. It serves up reasonable performance under air or water, and it doesn't inconvenience you when it comes time to swap between them.
We're comfortable giving this card our Approved award for doing exactly what it set out to. However, we have a hard time recommending it, particularly given an $860 price tag. It may work well in certain niche applications, but for enthusiasts who know that they want air or water cooling, you'll either find cheaper or better-performing purpose-built solutions in both categories.
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