For the past two decades, long-term planning for the x86 server estate has been predictable for infrastructure and operations (I&O) executives — but over the next three years, this planning process will undergo major transformation thanks to the introduction of a potentially disruptive option for servers: very low-power, mid-performance ARM-based servers. These servers promise two to four times the density, with performance exceeding that of low-power x86 options at a fraction of the power of even the lowest x86 offering. The net result is that I&O executives will have a new option for building out large-scale server farms for applications where the maximum number of servers and lowest power are more important than the fastest execution of a single thread. But three changes must occur for this to happen: 1) better ARM server road maps; 2) more robust ecosystems for system design; and 3) better software and OS support. Forrester expects that these three factors will emerge and trigger accelerated development of low-power and dense options by AMD and Intel.