Hi wootwhoo, here is the link for your Compaq Presario 7940 Desktop 201479-001.
Everything you need is listed within this link. It's a matter of looking. Since you need help setting up your bios settings. Than the link below will help you through it. I did not find a download for the manual. (Which is what I'm used to using for guidence for setting up bios's).
Now this page/link will walk you through setting up the bios.
All you need to do is scroll down the page. Compaq has pictures to help. Without the board & all it's connected parts I can't walk you through this but I can help some.
If you get stuck you can post back here & I'll try to help you out.
Compaq is unknowing which key to press to enter your bios.
This is how it works. Just after powering on the PC start pressing the F10 key every 2 seconds. The main menu of the bios will open. If, F10 does not open you to the bios we'll have to try some other F keys. (You can only try one F ke at a time).
Try the F2 key next & than the F1 key & the F12 key. One of thses will open the main menue.
It should help you to know most of the settings will already be set to their defaults. (Like most boards are). If your not sure you can set default settings at the main menu. Save & exit. The PC will auto restart. Go back into the bios by pressing the correct F key. Normal items to set are (Time & Date) at the main menu.
You should see your cdrom listed & hard drive listed. Things you want to turn on. Audio should be set to Enable or on if you do not have a seperate sound card. Same for video. Memory & CPU settings (No settings). They usually are already set. Boot will need to be set. Normal is. Floppy Disk is first, 2 is CDROM & 3 is hard drive.
First time through a bios will be a wee bit tough. So read twice & set once. Follow Compaq's instructions.
When in doupt, ask.