To perform diagnostics on a Dell computer, reboot the computer, and press the F12 key before the Windows screen appears. On the black boot-menu screen, use the direction keys to select Diagnostics or Utility Partition, depending on the model of the Dell computer.
If Windows asks you some questions, provide the correct answers, and then press any key to boot the utility partition. On the hardware-diagnostics screen, select Custom Test, tick the check box next to Non-interactive Tests Only at the top of the window, and then select All Devices on the left-hand side of the window.
Click Run Test to view the current problems with your Dell computer. If there is no error message displayed on the screen, check for software or network-related problems. For network-related problems, contact your Internet service provider.
Alternatively, if the Dell computer connects to the Internet, go to Dell.com, click Support, select View All Support, and then click Go to Quick Test under Online Diagnostics. On the new page, click the Run Quick Test button. The Dell online diagnostic tool scans and detects problems with the hard drive, processor, memory and disc drive of your Dell computer. After detecting an error, the diagnostic tool recommends further troubleshooting procedures, fixes the problem automatically, or provides a list of compatible replacement parts.