Motherboard shuts down before booting !

Check the ram. If its not the ram, take the heat sink off the processor and reapply arctic silver ( thermal paste) to the processor

try Ubuntu bootable disc or usb to boot from that. Ubuntu is a free operating system. you can use Ubuntu without actually installing it. you can run Ubuntu from a bootable disc or usb ......
such are called live CD or live usb.
running Ubuntu you can access the hard discpartition and hence your data and take backup os that in external media or another partition.

yoy can download Ubuntu freely. also you can order ubantu disc free of cost, even no delivery charges by post. just register and order Ubuntu from www.ubuntu.com

What Operating System are you running - if Windows what version XP, vista, 7? When is it shutting down, after you get into Windows (or other OS) or when trying to boot up? Are there any error messages? New machine or old machine - if old has anything changed? How long does the system stay working before it shutsdown? Is it getting too hot, fans blocked etc?
Lets start by working out if it is the hardware (Dell and devices connected) or the software (Windows etc) It is difficult to know without more details of the problem but here are my best suggestions
Try safe mode - running windows try in safe mode (F8 when starting windows), check error logs
Test the hardware - I would start by disconnecting all external devices, USB disk and other devices. If possible also remove any extra boards you have added to the machine. Even the mouse, USB sticks, anything plugged in (but leave the keyboard). Try this, do you get the same problem.
Test the OS - If you have a live CD such as Ubuntu (can be downloaded from here: http://www.ubuntu.com/desktop/get-ubuntu/download ) then try booting the system from this and see if you still get a problem
Can you run a virus checker on it, how long does the machine stay running. You can try downloading from here from another machine - http://www.avg.com/us-en/avg-rescue-cd-download and making a CD, run the rescue anti virus.

It sounds like your windows OS installation has been corrupted. Your computer might have a recovery partition like many HP models do.
Try hitting F11 when you first turn on the computer (watch the screen in the corners. It may say something like hit "F2 to go to BIOS or F12 to choose a boot device/ etc. Each computer is different in this regard).
If you can get into the recovery partition you may be able to do a windows repair. Alternatively, if you have your windows disc you can boot off the cd and run the windows repair tool like that.
I would HIGHLY recommend manually backing up any and all important files first. If you have a USB enclosure use that to pull the drive out and hook it up to another computer. If you dont then I would run a bootalbe version of linux or something and transfer your files to a USB drive or burn to a cd. See here to download ubuntu.

Sounds like you have a motherboard failure. This problem is very common with some HP laptop models, but not limited to HP unfortunately.
The problem is with the FSB controller chip that handles the work of the hard drive, dvd, keyboard, mouse, USB ports. In time, some pins from this chip lose contact with the motherboad which causes the laptop to experience random freezeups, slow responsiveness of the mouse and keyboard, and in some more extreme cases, the laptop gets stuck at the startup logo (The Toshiba screen), and in some cases even the startup logo is dimmed a bit.
There are two options: get a replacement motherboard, or fix the one you have. The repair of a non booting/random freezeup FSB problem is not too difficult, but you will have to open up the laptop. If you follow the link above, you won't need any special tools other than a screwdriver. The other option is to opt for a reflow of the FSB chip with a hot air gun.

Hope this helps. Please consider a Thumb Up vote for this post. Thank you.

1. I would suggest finding out which model Eee PC you are using and the hard drive size & type (4GB SSD, 160GB SATA, etc...). If you have less than 4GB, I would probably recommend using another Linux distro, as the Netbook Edition of Ubuntu is pretty heavy.

2. Next, I would probably suggest plugging in the Eee PC (Software/OS installation is very power intensive).

3. Download your distribution (Ubuntu Netbook Edition or Desktop, etc).

4. Download a copy of unetbootin for your PC (unetbootin.sourceforge.net -- There are Linux & Windows versions available.)

5. Using a USB thumb drive (USB Memory stick), you will want to wipe the drive (format using FAT/FAT32 filesystem).

6. Run Unetbootin, selecting the proper USB thumb drive & ISO image from the Ubuntu website.

7. After Unetbootin is finished, close it and safely disconnect the USB drive.

8. Next, plug the USB thumb drive into the Eee PC.

9. Turn on power to the Eee PC & after seeing the initial BIOS splash, hit the ESC key on the keyboard. This should bring up a boot selection screen. Using the arrow keys, select the appropriate USB drive and hit Enter (Return).

10. If all goes well, you should be running Ubuntu Desktop/Ubuntu Netbook Edition as a live desktop. (The installer is a link on the desktop.)

11. There are several step-by-step guides out there, so check them out, if needed. The installer should be very simple on this type of hardware, etc.

Good Luck!

--TaoBeastie

soks3d,
With the system shut down, unplug the power cable from the power supply. Open you're case and pull the memory from the system wait a minute than reseat the memory. Re-connect the power cable to the power supply. Try booting the system and enter the bios menu. (Pulling the memory will clear any memory resident virus). This has nothing to do with the alarm buzzer sound you heard. Typically the alarm sound is generated by the CPU. It's an audible warning that the CPU is over-heating. The CPU will shut down you're system so as not to damage the motherboard and CPU. (Suggest you check the CPU fan for dust build-up. Use canned air to help remove any build-up. You can also use a clean paint brush to help remove any dust from under each CPU fan blade.
It's also possible that the CPU fan is running far too slow and may need to be replaced.
See page 3-23 in you're user manual.
3-8. PC Health Status.
Open the link provided below for a new heat-sink and fan assembly for a socket 462;
http://www.directron.com/a4004d.html
If the CPU fan and heat-sink assembly seems clean it is also possible that the thermal grease / thermal tape between the heat-sink and CPU is too old and needs to be replaced. (Save this check for last).
Below is the link for you're motherboard;
http://www.abit.com.tw/page/en/motherboard/motherboard_detail.php?pMODEL_NAME=KV7-V&fMTYPE=Socket+A

Cheers'
Mike

Try booting up with a different operating system from your CD drive.

You can try Ubuntu 9.04 wich has a full operating system in a CD. you can even connect to the internet from this CD.

Systems that shut down after being powered on can point to an over heating of the CPU. Other factors come into play with overheating. Too much dust build-up on & under the CPU fan blades. Dust builds up in-between the heatsink fins (Thus the CPU fan can not cool the CPU chip.)
The CPU fan may be running too slow. When the PC system shuts down it’s saving you from hurting the system. You did not list the model number of you're system. Check you're system & clean the mentioned parts. Use canned air & a dry clean small paint brush to help remove possible dust buildup blow the dust away with the canned air.

Mike