Need an on-line owners manual for Dell dimension dim 2400

Assuming your question concerns the Dimension 2400, the is a section devoted to removing the computer covers in the service manual here
http://downloads.dell.com/Manuals/all-products/esuprt_desktop/esuprt_dimension_desktops/dimension-2400_service%20manual_en-us.pdf
If your product was the inspiron 519 look here
http://downloads.dell.com/Manuals/all-products/esuprt_desktop/esuprt_inspiron_desktop/inspiron-519_Service%20Manual_en-us.pdf
23.February.2015

Manual:
http://support.dell.com/support/edocs/systems/dim2400/en/F75560LRs.pdf

Specs:
http://support.dell.com/support/edocs/systems/dim2400/en/sm_en/specs.htm

http://support.dell.com/support/topics/global.aspx/support/my_systems_info/manuals?c=us&cs=19&l=en&s=dhs&SystemID=DIM_PNT_P4_CEL_2400
This a link to get an owners manual from Dell for your system, if you don't already have one. There should be a toubleshooting section as well as sugesstions on how to get out of modes. Ifyou need help with this, let me knowin "add comment' at end of solution.

Try this website..this is a manual for Dell Dimension 2400 PC Desktop
it includes how to remove the cover of your tower. Check it out..
http://www.andovercg.com/datasheets/dell-dimension-2400-series.pdf

Go to the Dell website. Under Support, at the upper right corner, type in 'Dim 2400 1-1-2 beep codes. The first thing that comes up is 'Advanced Troubleshooting Dell Dimension 2400 Series". Half way down the next page under 'Beep Codes' you'll find Code 1-1-2, the cause of which is 'Microprocessor register failure.' This probably means you'll have to take your 'puter into the shop to get it repaired.

Here you go samacriano... http://www.retrevo.com/support/Dell-2400-Desktops-manual/id/929bh737/t/2/
Owners Manual, setting up printer, etc. Just follow the download link! Hope that helps! -WhiteHatH4x0r

I'm really not sure what you mean by "P7 plug", and without knowing more about your system and OS... I generically searched Dell Support page for Dimension 2400 and found a page of driver downloads (76) (if you install, make sure you do them in order. instructions are on the page. just go to Dell support and put in your service tag # or search generically)What I did find is an owners manual, and if yours has been misplaced (like most of mine) just follow this link. P.S. I still don't know P7 but maybe the answer you need is in there. Best wishes and good luck. -jmattes I looked again, sorry it's a DC plug but I didn't see where it goes. There's a link for service manual there too. http://supportapj.dell.com/support/edocs/systems/dim2400/en/index.htm

http://www.fixya.com/support/p349042-dell_dimension_2400_pc_desktop/manual-14417/page-9

http://drivers.softpedia.com/progDownload/Dell-Dimension-2400-Broadcom-4401-LAN-Driver-Download-40466.html

Motherboard manual for this model is not available.

However you can download the full user manual here.

You find main info on motherboard and on diagnostic code in the manual.