Configuring and Customizing Dell PowerEdge R7725 Servers

Imanmzm,

While you can have just two dimms, the R7725 requires two processors, as seen on page 26 here. 
I also confirmed this through the Dell sales page, and it won't let you unselect the second processor.

Let me know if this helps.

@DELL-Chris H ​ Thank you for your response. Do all dual-socket servers require two CPUs for setup and boot, or is it specific to this server model?

Hi, not really whole dual socket servers require two processors. I don't have such a list but I know some dual socket servers may operate with just one processor. But this one needs two sockets.