original msg.(clipped)

<<<< Thank you so much for offering help. I still can't get it to boot. I have tried all your suggestions. I just tried the ram in another computer and it worked fine and showed the correct amount so I now know it's not the ram that is bad. It has to be something on the motherboard. Maybe a bad ram slot?

Gloria >>>>

...mmmmmm very surprised because this is what dell manual for xps 400 says.

(i don't think it could be the ram slot)
 
if diagnostic lights  1 & 2 DO NOT BURN and 3&4 BURN THEN

" Memory modules are detected, but a
memory failure has occurred.
• If you have two or more memory
modules installed, remove the
modules, reinstall one module (see
page 74), and then restart the
computer. If the computer starts
normally, reinstall an additional
module. Continue until you have
identified a faulty module or
reinstalled all modules without error.
• If available, install properly working
memory of the same type into your
computer (see page 74).
• If the problem persists, contact Dell
(see page 126)."


the manual also has further diagnostic measures as given below

<<<< Dell Diagnostics
CAUTION: Before you begin any of the procedures in this section, follow the safety instructions in the
Product Information Guide.
If you experience a problem with your computer, perform the checks in "Solving Problems" on
page 37 and run the Dell Diagnostics before you contact Dell for technical assistance.
NOTICE: The Dell Diagnostics works only on Dell™ computers.
1 Turn on (or restart) your computer.
2 When the DELL™ logo appears, press <F12> immediately.
If you wait too long and the operating system logo appears, continue to wait until you see the
Microsoft® Windows® desktop. Then shut down your computer (see page 63) and try again.
3 When the boot device list appears, highlight Boot to Utility Partition and press <Enter>.
4 When the Dell Diagnostics Main Menu appears, select the test you want to run.
Dell Diagnostics Main Menu
1 After the Dell Diagnostics loads and the Main Menu screen appears, click the button for the
option you want.
2 If a problem is encountered during a test, a message appears with an error code and a
description of the problem. Write down the error code and problem description and follow
the instructions on the screen.
If you cannot resolve the error condition, contact Dell (see page 126).
NOTE: The Service Tag for your computer is located at the top of each test screen. If you contact Dell,
technical support will ask for your Service Tag.
Option Function
Express Test Performs a quick test of devices. This test typically takes 10 to
20 minutes and requires no interaction on your part. Run
Express Test first to increase the possibility of tracing the
problem quickly.
Extended Test Performs a thorough check of devices. This test typically takes
1 hour or more and requires you to answer questions
periodically.
Custom Test Tests a specific device. You can customize the tests you want
to run.
Symptom Tree Lists the most common symptoms encountered and allows
you to select a test based on the symptom of the problem you
are having.
Troubleshooting Tools 57
3 If you run a test from the Custom Test or Symptom Tree option, click the applicable tab
described in the following table for more information.
4 Close the test screen to return to the Main Menu screen. To exit the Dell Diagnostics and
restart the computer, close the Main Menu screen.>>>>.

if you are quite convinced that it is a motherboard problem then it may need specific tools and more knowledge than i have to troubleshoot.

you can check the " capacitors" (sort of very small cylinders") normally surrounding the CPU and see if any have a blown up top ( sort of conical instead of very flat)

also place the palm of one of your hands on the metal surface of your hard drive ( this will depend on how DELL have mounted it....very proprietery)
and see if you feel a slight vibration to check that the HDD IS OK.
hereagain latest HDD'S have barely audible vibration.

HTH and good luck---Venkat

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