We just had several 3PAR 7400 arrays installed with individual physical service processors. The base model of each is a HP ProLiant DL320e Gen8, a Xeon E3 equipped with a single hard drive.
Here's a photo of one of the units from the rear:
For power, our PDU's are reporting each is pulling around 0.3-0.4A @ 208V, so about a reasonable 60-80W of power. Each has only a single power supply, so don't expect any redundancy. I know that the DL320e does support redundant power supplies, but I doubt HP would make that an available upgrade for the service processor.
Networking requires only a single Ethernet port, which is used to connect up through your firewall to report back to HP, and to allow HP to perform remote diagnostic functions. The other Ethernet port is used for servicing by HP technicians. A serial console port is also available, but we were told it shouldn't remain connected.