Nothing will show up on the monitor

One solid beeeeeeeeeeeeeeep, or a beep.. beep .. beep, or a sequence of beeps?
Whatever the beeping is, you should look up in the dell website, or the documentation for your model, and diagnose what that beep means.

I don't think the monitor, connected or not, will cause any beeping. Your problem is more early than that, such as a BIOS error, some memory error, or perhaps even a power supply error.

BTW, when you finally get past this beep, you should connect your monitor with a direct cable, and not use some adapter or converter cable. Even a regular old VGA cable would be good (assuming you have those sort of connections) to get you to a point to get the computer up again. Leave the adapters out until you don't have other problems to worry about ... one thing at a time.

The PC system you got was the one that worked all together originally? If not and you changed the video setup in some way, you need to return to that type of setup just to get it working. You can then change the video setup as required but outside of the beeping if not video related, could be more than one problem. As for the beeps, that has to be taken care of. It's offering a bios beep code that points to some problem, so count the beep sequence and look-up the bios error codes. if you haven't already closely inspect the innards and verify its all connected and FULLY SEATED. I assume also, the system was working before you brought it home and saw it working.

tada -----Willy