Great article on how Facebook is not buying from HP, Lenova or the like but instead creating its own hardware sleds in its labs . It has 5 different server variants and can pull them as it chooses , as well as making corrections without having to pull full servers.
For the open hardware movement , especially in Asia, this is their research work done for them !
http://www.theregister.co.uk/2014/03/05/facebook_lab_tour/