RE: Monitor randomly goes into power saving mode
A quick test of the added discrete video card would be to power the XPS 8300 off. Disconnect the power cable from the XPS 8300. Lay it down and open the cover. Disconnect the monitor from the video card. Remove the video card. Connect the monitor to the onboard video HDMI out port or the onboard video VGA out port. Turn the monitor on, then the XPS 8300. If it stays on using the onboard Intel video, then the video card may be faulty.