Some Intel CPUs have a scalability feature such as i7-4790:
Scalability: 1S Only
There is no explanation about what this is. Could somebody explain it to me?
I suspect the Scalability: "1S" means it only supports single socket setups. So you cannot create a system with two sockets and fill only one until you need your system to scale up to handle more load and then to accomplish that, simply add a second processor. You can do that with Xeon processors though, for example E5-2440 v2 has "2S Only".