What are these server? Are they beneficial over to others as per performance?

This should help some with a basic explanation:

http://en.wikipedia.org/wiki/Cobalt_RaQ

The RaQ was a small server appliance that was popular in the late 90s and early 2000s. This forum is here for old-timers to reminisce about their younger years. :D

If you need a small, cheap, low-power server, Atom servers are a good modern choice.