The device will not boot.
Your computer will not boot.
Check to see if the power light is on. If it is not, the computer is either not getting power from its source or is turned off. Reseat the power cable in the power connector on the back of the computer. Confirm that all connections to the power supply, motherboard, and front panel are secure. Confirm that any power strips being used are plugged into a working electrical outlet and are turned on.
If the power light is green and the computer is not responding, check the diagnostic lights on the front panel.
- If the second light from the right is green, reseat the processor.
- If the two rightmost lights are green, there may be a problem with the memory modules. You are going to have to reseat (reinstall) the memory modules, adding one memory module at a time, restarting your computer after each installed module to see if it is faulty. Please refer to our guide on reseating and replacing memory modules.
- If the rightmost and second from left lights are green, there may be a problem with the graphic card(s). You are going to have to reseat your graphics car(s). Please refer to our guide on reseating and replacing graphic cards.
For more details, see page 66 of the Dell XPS 720 H2C owner's manual.
There are error messages regarding memory.
When you try to add additional programs, documents, or data, you receive an error message saying that you have insufficient memory.
Background files and programs
Save and close any open files and exit any open programs you are not using to see if that resolves the problem. Your computer will sometimes stop installing new programs because other programs are up and running.
If closing programs does not solve the problem, the problem is going to lie with your memory modules (memory cards). At this point, there are two problems: 1) Your memory modules are not properly communicating with the computer, or 2) You do not have sufficient memory. To reseat your modules (removing and reinstalling the memory modules), or install additional memory into your computer, please refer to our guide on reseating and installing memory modules.
The display stutters or has low quality.
The display quality of your screen is very poor when you're playing a video, movie, or game. The FPS may drop, the display may stutter, or there may be a delay between user input and the display on the screen.
Monitor cable connection
Check that the DVI or VGA cable is properly connected to the computer and the monitor. Make sure the screws on either side of the cable are very tight when plugging it in. If you are using the optional DVI-to-VGA adapter, ensure that the connection between the cable and the adapter is secure.
Interference from external power sources
It is possible for external power sources to emit electromagnetic radiation that will cause interference in the display of your monitor. Examples include fans, fluorescent lights, halogen lamps, and other electrical devices. To see if this is the problem, turn off nearby devices to check for interference.
Note: If your speaker system includes a subwoofer, ensure that the subwoofer is positioned at least 60 centimeters (2 feet) away from the monitor.
Bad display settings
Sometimes, your display settings are not set to a specific standard required by the video, movie, or game. To access and change your display settings:
1 Click Start→ Control Panel→ Appearance and Themes.
2 Click the area you want to change or click the Display icon.
3 Try different settings for Color quality and Screen resolution.
1 Click Start → Control Panel→ Hardware and Sound→ Personalization→ Display Settings.
2 Adjust Resolution and Colors settings, as needed.
Bad graphics card
If all of the above is not the problem, you have a faulty graphics card. Check out the repair guide for installing a new graphics card.
No sound is coming from my speakers
The speakers are not emitting sound. The computer may say it is outputting sound even though nothing is coming out.
Check to make sure your speakers work by plugging them into another device and testing them. Also make sure that your speakers are not muted and they are plugged in securely. The speaker output is labeled with a headphones symbol on the front panel. On the back panel it is labeled with a green square.
Sound card or driver issue
Click start and type "drivers" into the search box. Press enter and the Device Manager should pop up. Expand the drop-down menu called "Sound, video and game controllers." If no sound driver is listed under this menu then you have a problem with your sound card.
It is possible that your sound card is not installed properly. If this is the first time you are using the computer or you have recently opened up the device, it is possible the sound card is not installed securely. To make sure the sound card is installed correctly, shut down the computer then open up the computer by removing the side panel and locate the sound card. The sound card is found near the bottom of the device and corresponds with the audio plug on the back panel. Flip the blue switch and pull the card out carefully. If the card is difficult to pull out, firmly grasp it with two hands and pull with an evenly distributed force. Push the card back into the slot. Make sure it is all the way in and it went in straight. Secure the card with the blue switch and power on the computer.
If the sound problem still occurs and there is still no audio driver listed in the Device Manager, then there may be a problem with the sound driver. This problem can be fixed by prompting Windows to update which will restore faulty drivers or by going to the sound card manufacturer's website and downloading the latest driver.
If you now have an audio driver listed under the Device Manager and the problem still occurs, your sound card is likely faulty and needs replacing.
For more information regarding reseating or reinstalling the sound card, check out our sound card repair guide.
The device does not read any CD-Roms.
Your computer will not read disks you put into the disk drive.
Although this may seem a little redundant, make sure the disks you are inserting into the disk drive are clean. Any dust accumulated on the disk surface may deny the internal reader to properly read the disk. DO NOT apply a towel or napkin directly to the disk surface to remove dust. Instead, wash the disk and then use a soft cloth (preferably a microfiber cloth) to dry it up. Wipe in circular motions starting from the inside of the disk to the outside.
Other programs are open
In the certain cases, the disks may not be readable due to other programs using the disk drive. These programs may be attempting to use the drive, which keeps Windows from accessing the disc. To solve this, close any program that may be using the drive. If you're unsure which programs to look for, try closing these: Roxio family of products, Power DVD, WinDVD, Media Direct, Windows Media Player, or Nero Burning ROM.
If the cleaning the disk or closing additional programs does not work, the problem may lie in your drivers. For clarification, a driver is software that allows your computer to communicate with hardware or devices. Without drivers, the hardware you connect to your computer will not work. In your case, the driver for your disk drive may not be detectable by the computer. You will need to reinstall the driver from the Dell's website.