You can find detailed information about supported hardware in these Sun Fire X4170, X4270, and X4275 Servers documents.
“About Server Features and Components” in the Sun Fire X4170, X4270, and X4275 Servers Installation Guide
“About the Sun Fire X4170, X4270, and X4275 Servers” in the Sun Fire X4170, X4270, and X4275 Servers Service Manual
Within those documents, you can find information about supported hardware for these and other components:
Processors
Memory
Storage drives
Host bus adapters