With have Dell Optiplex 780 PC and have problems

Hi mmm it sounds to me like your motherboard has got some problems. sometimes running system tests through the boot menu may help but should indicate weather you need a new motherboard or not. Sometimes a good clean inside computer is the way to go as well... Hope this helps
Kindest regards

open lid
remove cables from HDD
if is with factory caddy it just slides out (blue caddy)
move plastic tabs of caddy inward and it just slidesout
some PC were modified here and I can not see yours now.

Sounds like a problem of non-detection by the system. If the drive is missing from My Computer then it definitely is a non-detection issue. Try using this file (it's an exe when unzipped) and only required double-clicking.


http://www.geekstogo.com/forum/files/file/8-cdgone/

You could try unconnecting the USB hardware and then start the computer. But, with Dell you will most likely need to have the keyboard plugged in. Then if the computer starts, you can fit each item until it stops. But, the Dell USB controller is renowned for being weak. You may need a USB PCI card to continue using the computer, they are a lot cheaper than a replacement motherboard or a new computer.

Go to Dell Support > Optiplex 780 Desktop PC > Manuals & Documentation > Dell Optiplex 780 Service Manual,

http://www.dell.com/support/troubleshooting/us/en/19/Product/optiplex-780

Diagnostics > Diagnostic Lights,

"Problem Description - A possible expansion card failure has occurred"

"Suggested Resolution -
1) Determine if a conflict exists by removing an expansion card (Not a graphics card) and restarting the computer.

2) If the problem persists, reinstall the card you removed, then remove a different card and restart the computer"

Be SURE to follow Anti-Static Procedures.

Regards,
joecoolvette

Here is a link to your computer's service manual that has a chapter on diagnostics including Beep codes:
ftp://ftp.dell.com/Manuals/all-products/esuprt_desktop/esuprt_optiplex_desktop/optiplex-780_Service%20Manual_en-us.pdf
This for the desktop model. If you have a different model you can choose from this link:
http://www.dell.com/support/troubleshooting/us/en/19/Product/optiplex-780

Dell has all of their computer's drivers online, in their Support section. You will need to input the Service Tag of the computer to find the ones for you.

turn on your dekstop. press the F2. Make sure the hdd is detected. it should display the name of your harddrive. then find the boot order and set the hard disk as the first priority boot order. press f10 and save.

The desktop could be overheating and shutting down.
To fix this problem, please click on this link :-

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