that power edge 2900 is ancient stuff. It has a huge power consumption to go with those dual power supplies.
The updated version which is a R7xx series is better and uses less power.
If you had asked me about the network port with the spanner I could have told you that it is the iDrac or iLo port.
Allows you to turn the server on remotely if need be and also allows you to check the state of you hardware.
We use the iDrac ports all the time. life saver really. saves you from having to go into work on the weekends to power cycle a server.
BTW, if you can manage to get an R730 in 2 RU form, then you are set for a long time. It might cost you an arm and a leg though.