What are the hardware requirements for being a validator node?

Validators need to provision and operate their own server or servers with sufficient network capacity and data center operational integrity. Servers can operate in a public or private cloud setting or on locally provisioned hardware, provided they meet SLA requirements. A particular requirement for servers is that they operate Intel SGX.
Intel SGX (Software Guard Extensions) is a set of instructions that increases the security of application code and data, providing added protection from disclosure or modification. Developers can partition sensitive information into enclaves, which are areas of execution in memory with more security protection. It is recommended that all nodes in a validator set be Intel SGX servers although it’s also possible to set up a network nodes with a certain ratio of Intel SGX servers to non-SGX servers.
Other node requirements include Ubuntu 18.04 or above, 200GB of attached storage, and 32GB RAM.