Update = After verifying ownership and completing troubleshooting, a DELL agent setup system exchange.
I am so sad and so over it. My tower has been nonfunctional since Feb 4. Dell sent out the wrong parts 4 x, and won't believe me or  either of the two techs most recently here that the harddrive listed in my configuration is not the one in my computer, and the one they sent has no where to sit.  I've waited for techs that never came. I've waited on horrible hold music with Dell and Unisys for hours - literally tens of hours - and I can't concentrate while holding and hearing that horrible sound. I've repeated the whole history so many times that I can't do it any more. I don't trust Dell to send out the right parts, as they will just hold to what is in the configuration document.  I contacted Dell today and said I can't do it any more. Either refund or exchange. Call this number - call, hold for 30 minutes ; get to customer service, "I can't help you, I'll transfer you to technical solutions" - turns out it is the same basic support that hasn't helped me. I tell them I am losing it I can't do this any more, "I can't help you. you need to talk with customer solutions"  So, having lost most of the time I had gained by purchasing a 2500 computer, I told the last rep I'm calling my attorney. I called this afternoon, and they are getting back to me tomorrow, and I want to know to whom they should connect. It's either they get to talk to someone who can help, or I have to sue, which I SO don't want to do.  I've bought everything from Dell because I like having one vendor I trust. I will need to return the huge monitor I just purchased and find a new vendor which makes me very sad. Thank you!!! 
Precision 7820, bad service