The newest GPU racks can be cooled with water at 45°C. It reads like a typo. For anyone building AI infrastructure in the Gulf, it's the most useful number in the spec sheet.
It works because the heat comes off the chips through cold plates, straight into liquid, and the loop runs hot. Hot enough that outside air can carry it away through dry coolers in a closed loop, with no water evaporated at all. NVIDIA puts a conventional cooling-tower design at roughly 2.6 million gallons of water per megawatt per year, close to 10 million litres. A dry-cooler design takes that to near zero.
The catch is in the small print. Chiller-less operation is promised "in favorable climates". A Gulf July is not a favourable climate. When the air outside is in the 40s, it can't pull a loop back down to 45°C on its own, and something else has to cover those hours.
That something is water or electricity. Spray the coolers, or run chillers. Both cost more here than the brochure assumes. Much of the region's drinking water is desalinated, and desalination runs on power. Chillers draw from the same grid connection the GPUs are already queuing for.
So for a Gulf AI build, liquid against air is a settled question at these densities. The open one is how many hours a year the site sits above the line, and which of the two you've chosen to pay with for those hours.
Ask that before anyone prices a chiller. Ask who holds the water rights, too. The answers will tell you more about the site than the GPU count does.