This says nothing about the esata port on the dell as being the same as an esatp port. I already know about sata drives some needing 5v and some 5 and 12v. I also know that a USB only supply's 5V, that's why I asked. However esatap provides both 5V and 12V. If you don't know why answer?
So If I read between your lines Folks do want to hear know, yes?
I assume you think the Dell is NOT a esata/p port but only a esata and usb.
In computing, eSATAp (also known as Power over eSATA, Power eSATA, eSATA/USB Combo, eSATA USB Hybrid Port (EUHP)) is a combination connection for external storage devices. An eSATA or USB device can be plugged into an eSATAp port. The socket has keyed cutouts for both types of device to ensure that a connector can only be plugged in the right way.
eSATAp combines the functionality of an eSATA and a USB port, and a source of power in a single connector. eSATAp can supply power at 5 V and 12 V.