Dell Latitude C840 - Manual (Page 82)

The 70-W AC adapters used in some of Dell's older portable computers can be used with your computer, but they will decrease system performance. Likewise,
you can use the 3800-mAh and 3600-mAh batteries from older Dell™ computers, but these lesser-capacity batteries will discharge faster. Using less-powerful
AC adapters or batteries may cause you to receive a WARNING or a SYSTEM CONFIGURATION ERROR message similar to the following:
WARNING: 70 Watt AC adapter detected. System will not be capable of running in full performance without a 90 Watt AC adapter.
Docking Power Considerations
The 4400-mAh battery supplied with the computer is not designed to support both the computer and a docking device. For optimum system performance,
always use the 90-W AC adapter (with or without a battery installed) when using the computer in a docking device. You can identify the 90-W adapter by the
lighter-gray tip on the connector that plugs into the computer or docking device.
Using a 70-W AC adapter will cause the computer to run in reduced-performance mode and may display an AC adapter WARNING message.
If no AC adapter is detected when the computer is docked, the computer does not power up.
Docking While the Computer Is Running
To accommodate the initial power surge when connecting to a docking device with the computer running in normal (non-power conservation) mode, a 90- or
70-W AC adapter and at least one battery (a 4400- or 3800-mAh battery) must be installed in the computer. The computer will then run in either full-
performance or reduced-performance mode, depending on the battery/AC adapter combination installed.
AC Power Loss While the Computer Is Docked
If a computer loses AC power while docked, the computer immediately goes into low-performance mode and displays an appropriate WARNING message.
Error Messages
If the message is not listed, see the documentation for the operating system or the program that was running at the time the message appeared.
NOTICE: Do not use an AC adapter rated under 70 W or a battery rated under 3600 mAh in this computer. To do so will cause indeterminate results,
including data loss and/or immediate system shutdown. Using one of these lower-powered components will cause a SYSTEM CONFIGURATION ERROR
message to appear.
NOTE: If you want to upgrade the AC adapter for an existing Dell docking device, you can purchase an additional 90-W AC adapter from Dell.
Auxiliary device failure — The touch pad, track stick, or external PS/2 mouse may be faulty. For an external mouse, check the cable
connection. Enable the Pointing Device option in the system setup program. If the problem persists, contact Dell .
Bad command or file name — Ensure that you have spelled the command correctly, put spaces in the proper place, and used the correct
pathname.
Cache disabled due to failure — The primary cache internal to the microprocessor has failed. Contact Dell .
CD drive controller failure — The CD drive does not respond to commands from the computer. See " Drive Problems ."
Data error — The floppy or hard drive cannot read the data. See " Drive Problems ."
Decreasing available memory — One or more memory modules may be faulty or improperly seated. Reseat the memory modules and, if
necessary, replace them. See " Adding Memor y."
Disk C: failed initialization — The hard drive failed initialization. Run the Hard-Disk Drive tests as described in " Dell Diagnostics ."