The hardware requirements for IBM Connections are very much dependent on the type of implementation you are going with. It is also affected by the operating system that you choose. Typically, Windows server deployments requires more available memory than Linux due to the overheads of the operating system. Both operating systems require broadly the same amount of disk space. Compute cores and processors have a strong influence on the performance of IBM Connections, as does the configuration and tuning of the Java Virtual Machines which IBM Connections runs in through WebSphere.
Choosing a 64-bit operating system is a good first step because you can allocate more memory to the JVMs. Using more processors can improve performance when you have maximized the use of the JVMs. Be aware that you have to check your licensing situation with IBM when it comes to adding cores and processors as you might be licensed on a Processor Value Unit basis.
As a rule of thumb, for a small deployment serving up to 1000 users, the hardware configuration we chose was as follows: