[. . . ] HP shall not be liable for technical or editorial errors or omissions contained herein. Second Edition: April 2010 Document Part Number: 593731-002 Product notice This user guide describes features that are common to most models. Some features may not be available on your computer. Safety warning notice WARNING!To reduce the possibility of heat-related injuries or of overheating the computer, do not place the computer directly on your lap or obstruct the computer air vents. [. . . ] Adjusting the gamma of an image allows you to change the brightness values of the middle range of gray tones without dramatically altering the shadows and highlights. A lower gamma setting makes grays look black, and makes dark colors even darker. Backlight Comp--Compensates in cases where a subject with a large amount of background light would otherwise be obscured by streaking or silhouetting. For information about using the webcam, select Start > Help and Support. Webcam (select models only) 45 5 Power management Setting power options Using power-saving states The computer has two power-saving states enabled at the factory: Sleep and Hibernation. When Sleep is initiated, the power lights blink and the screen clears. Your work is saved to memory, letting you exit Sleep faster than exiting Hibernation. If the computer is in the Sleep state for an extended period or if the battery reaches a critical battery level while in the Sleep state, the computer initiates Hibernation. When Hibernation is initiated, your work is saved to a hibernation file on the hard drive and the computer turns off. CAUTION: To prevent possible audio and video degradation, loss of audio or video playback functionality, or loss of information, do not initiate Sleep or Hibernation while reading from or writing to a disc or an external media card. NOTE: You cannot initiate any type of networking connection or perform any computer functions while the computer is in the Sleep state or in Hibernation. 46 Chapter 5 Power management Initiating and exiting Sleep The system is set at the factory to initiate Sleep after 15 minutes of inactivity when running on battery power and 30 minutes of inactivity when running on external power. Power settings and timeouts can be changed using Power Options in Windows® Control Panel. With the computer on, you can initiate Sleep in any of the following ways: Briefly press the power button. To reduce potential safety issues, use only the AC adapter provided with the computer, a replacement AC adapter provided by HP, or a compatible AC adapter purchased from HP. Approved AC adapter Optional expansion product Connect the computer to external AC power under any of the following conditions: WARNING! When you are charging or calibrating a battery When you are installing or modifying system software When you are writing information to a CD or DVD When you connect the computer to external AC power, the following events occur: The battery begins to charge. If the computer is turned on, the battery meter icon in the notification area changes appearance. When you disconnect external AC power, the following events occur: The computer switches to battery power. The display brightness is automatically decreased to save battery life. To increase display brightness, press f3 or reconnect the AC adapter. 50 Chapter 5 Power management Connecting the AC adapter WARNING!To reduce the risk of electric shock or damage to the equipment: Plug the power cord into an AC outlet that is easily accessible at all times. Disconnect power from the computer by unplugging the power cord from the AC outlet (not by unplugging the power cord from the computer). If provided with a 3-pin attachment plug on the power cord, plug the cord into a grounded (earthed) 3pin outlet. Do not disable the power cord grounding pin, for example, by attaching a 2-pin adapter. Plug the other end of the power cord into an AC outlet (3). Using external AC power 51 Testing an AC adapter Test the AC adapter if the computer exhibits any of the following symptoms when it is connected to AC power: The computer does not turn on. [. . . ] Follow the on-screen instructions to set up and create a backup. NOTE: Windows includes the User Account Control feature to improve the security of your computer. You may be prompted for your permission or password for tasks such as installing software, running utilities, or changing Windows settings. Refer to Help and Support for more information. Backing up your information 109 Using system restore points When you back up your system, you are creating a system restore point. A system restore point allows you to save and name a snapshot of your hard drive at a specific point in time. [. . . ]