Immersion-1 started as a project on a much smaller scale using traditional air-conditioning for cooling. It soon became apparent that traditional air cooling would impose many challenges on space and electricity usage. With 6048 FPGA chips, combining 890 million logic cells, Immersion-1 has become a massive prototype and proof of concept for a whole new generation of computing.
Since the special application tweaks the maximum performance out of each FPGA, they generate much more heat than in traditional FPGA applications. Often, FPGAs have to be throttled down or are not running at maximum performance due to cooling issues. In case of Immersion-1, the cluster would not be able to run on passive cooling and the FPGA chip temperature rises within seconds above its maximum specifications.
Only by using immersion cooling it was possible to build and run Immersion-1 with its very demanding cooling requirements. More than 90% of the electricity could be saved in comparison to traditional air cooling.
If ordinary servers would have been used to achieve the same computing performance, then more than 8,500 Dual Xeon 1U servers would have to be placed in more than 200 racks with 42U height. The power rating would be about 6.4 Megawatt generating around 45,000 tons of CO2 every year. That is equivalent to saving the same amount of CO2 as produced by 1.65% of all cars in Hong Kong.