[NAME] 23  Sure you're re-connecting the monitor to the right video port on the XPS 8500? When there's an add-in video card, NVidia or AMD, the onboard video ports are disabled. The onboard video ports are #5 (VGA) and #6 (HDMI). Ports on an add-in video card would be in the area marked #9: [IMAGE]
My XPS 8500 was working fine until recently I disconnected the monitor to use it on another computer to read some obsolete disks.  When I reconnected it to the XPS 8600, the monitor was black.  When I turned it off and back on, the power light came on white, the internal fan ran, there were no beeps, just a blank, black screen.  I have disconnected all peripherals, including the mouse and keyboard, as well as the data cables to the motherboard.  I have tried removing the motherboard battery, holding the power button down for about a minute, and restarting.  Nothing happens.  On one occasion, I forgot to re-install the battery.  This time I got the beeps indication a power failure for the real time clock.  When I removed the memory sticks, I got the two beeps indication no memory.  As soon as I plug the power cable in, the green light on the back of the power supply comes on and stays on.  A few times when I pushed the power button, the power light came on and the fan on the motherboard started, but shortly they both went off for a second or so and then came back on.  I have checked all of the USB ports and they seem to be active.  I got an identical replacement video card and that had no effect.  Any ideas what my problem is?  Thanks in advance.
XPS 8500, black display, no beeps, no nothing