Hp dc7900 powers up momentarily even when computer is off

NANDAKISHORE

• 304 Answers
• Posted on May 21, 2009

SOURCE: computer won't power up

This happens sometimes due to SMPS failures. Try to change with other SMPS with same watts.

If it happens same then the problem with the board.

Try to consult a technition.

Thanks & Regards

Nanda Kishore

SOURCE: HP Media Center does not power on

Sounds like your power supply has took a dive.

You can replace it yourself for really cheap $20-$50 or have a local repair shop or someone from craigslist for about $60-100.

It's really just four screws to remove the power supply and then you just put all the power connectors back. It's NOT hard if you just take your time and pay attention to what you are doing.

Best of luck!

SOURCE: I have HP 305W. When turns on the power, it stops within 5 scnds

sounds like your motherboard lost a control chip. that makes the power supply cycle off, when m/b doesn't send correct signals to continue boot.

SOURCE: Somenon put a power on password on a hp desktop

Turn the unit off. If you open the unit there will be a jumper to clear the CMOS and a battery. Remove the battery and then switch the jumper as silkscreened on the board. usually there are 3 pins currently crossed are 1 and 2. switch it to 2 and 3, press the power button then hold for a few seconds. unpress the button and remove the pwoer cord. press and hold the power button again for a few seconds to clear all power. reconnect the jumper to 1 and 2. put battery in and plug and boot. password should be gone.

in some units there is a "clear password" or "cmos password" jumper. crossing this will remove the password in those units.

SOURCE: HP Compaq DC7900 CD/DVD problem - computer does not read them

I guess the CD/DVD drive is not detected in my computer
Then you can follow the following steps:
CAUSE-It may happen due to some corrupted registry keys in the computer. We can follow the following steps to delete the upper and the lower filters.
RESOLUTION/ WORKAROUND-
1. Locate the following key in the registry: HKEY_LOCAL_MACHINE\SYSTEM\ControlSet
2. In some cases, there may be multiple ControlSets. You may see something similar to the following HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet002
Or
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet002
3. Select either CurrentControl Set or the lowest numbered ControlSet, for example, in the second list above, ControlSet001, and do the following.
4. Locate the following key and highlight it in the left window of the Registry Editor. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E965-E325-11CE-BFC1-08002BE10318}
5. In the right window, you should see something similar to the list below. There may be some variation in the listed drivers for the upper and lower filters. For example, the upper filters may list a driver other that PWD_2K. You may also see only upper or only lower filters:
LowerFilters = CDRALW2K
UpperFilters = PWD_2K
6. Delete the upper and/or lower filters.
7. Exit the Registry Editor and restart the system.
NOTE: If the computer still does not recognize the drives, go back into the registry and repeat the above steps for editing the registry for each of the ControlSets listed on the system.
Hope it works for u
All The Best !!!!