ARM has typically been more efficient, for both heat and power consumption, while losing out on computational power.<p>That&#x27;s enabled people to cram significantly more processing cores into a server rack.  4 years ago HP release a server line with 288 quad-core ARM processors in 4U, for a total of 1152 cores.  Obviously that introduces the complexity of needing code that is suited to massive parallelism.  Each processor there took up just 1.5 watts idle, 5 watts under load.  By comparison the Atom from Intel at the time had comparable performance, but consumed 8.5 watts, just over 70% more, and didn&#x27;t idle to as low consumption.<p>There are a number of problems that are significant with large scale data-centre operations, but power consumption and heat generation are way up there at the top.  In theory a data-centre filled with ARM based servers would give you comparable performance, but with cheaper electrical and climate control bills.<p>The emphasis there is on &quot;in theory&quot; :)  The reality at the moment is that companies have spent years trying to get ARM based, massive core count servers to be a thing, and it hasn&#x27;t really worked out.  Switching processor architectures is never something that can be done lightly.  Software has to be compiled and supported provided for it, and isn&#x27;t necessarily tuned for the ARM architecture.  The x86 architecture&#x27;s performance characteristics have been really well understood, and software likely designed with those characteristics in mind.<p>Historically ARM has also lacked Windows server support, and had very variable quality linux support (not helped by every Tom, Dick and Harry SoC company do the darnedest things in pursuit of creating &#x27;value&#x27;.)  As far as I&#x27;ve heard, they&#x27;ve since done (or started on?) a huge restructuring of the ARM path in the kernel to clean up the mess and provide significantly better customisation opportunities.<p>In part it has also seemed like a case of &quot;no one ever got fired for buying IBM&quot;.  You&#x27;ve only got a certain budget, do you gamble on an unproven (to you) architecture, or stick the the tried and tested Intel?