German overclocker Der8auer has created the world's first water block for the RTX 5090 Founders Edition, one of the best graphics cards. Der8auer showed off a prototype his team built on YouTube that is designed (primarily) to fit the RTX 5090 FE PCB and its sub-components. The block reduced temperatures from 73.8 degrees Celsius to 43.8 degrees C on the GPU core.
The prototype Der8auer's team built was entirely made of copper, including the cold plate and exterior cover plate. The block was designed as a proof of concept and, as a result, has no pleasing aesthetic touches, such as RGB lighting, save for a see-through glass cover on the top that allows visibility of the liquid flowing through the cold plate.
The cold plate alone is allegedly made of 14mm of copper and features several passageways to keep the entire GB202 die cool. Unlike previous generations of Founders Edition water blocks, Der8auer's 5090 FE block is a dual-slot form factor with a similar length and height as the RTX 5090 Founders Edition cooler.
Unfortunately, Der8auer's team had to keep the length the same as the stock cooler to account for the length of the ribbon cable connecting the outer display outputs to the PCB. Apparently, this ribbon cable can't be folded in any serious way without damaging it. If it weren't for this ribbon cable, Der8auer's team could have reduced the block's form factor to be more similar to the PCB size, which is much smaller.
Another problem Der8auer addressed with his prototype's block design was a lack of structural support they implemented for the PCIe slot. This usually wouldn't be an issue on mainstream PCBs. Still, the Founders Edition variant splitting the PCIe finger into its sub-component makes it more fragile than usual. The only thing holding it in place is the PCB with the installed water block.
Despite this issue, the water block performed exceptionally well in testing. Der8auer recorded an impressive 30 degrees Celsius drop in GPU temperatures and a 38 degrees Celsius decline in memory temperature compared to the stock Founders Edition cooler.
Der8auer did not disclose a release window for a potential retail version of his 5090 prototype water block. He specified that the issue regarding the PCIe slot would need to be addressed before shipping a retail version to the public.
