MOBO or CPU failure?

Do you have a question? Post it now! No Registration Necessary.  Now with pictures!

Threaded View

I built this computer a few years ago, and probably about a year ago
the monthboard and cpu. System has run fine until yesterday.
When I boot up I
get fans, lights but motherboard stays on MSI screen
and won't move nor can I
access the setup or Bios.
PSU is a 500, so have more then adequate power. Do you think the mobo
has failed
or the CPU? I believe I am running an AMD 3800.

Re: MOBO or CPU failure?

golfer749 wrote:
Quoted text here. Click to load it

The fact that the motherboard was able to paint the MSI screen tells you:

1) Boot block worked. And it successfully vectored to the main BIOS code.
    One of the jobs of the boot block, is to verify the checksum of the
    main BIOS code. As far as I know, the main BIOS code is what starts to
    put content on the screen. That is why I'm guessing you're running
    the main code right now, and are not stuck in the boot block.
2) Full screen logo was copied from the main BIOS code
    and placed on the screen. The main BIOS is a modular file
    system, and the full screen logo is a file within it.
3) Now, some part of the POST and boot sequence is failing.
    But since your full screen logo was enabled, you can't see
    any error messages. This is one reason, I *always* leave
    full screen logo disabled, as part of a build. It may be
    pretty, but in times of trouble, it gets in the way.

On a lot of motherboards, if you clear the CMOS, the defaults
for the BIOS are to *enable* full screen logo (which is stupid).
So even if you were to clear CMOS right now, chances are the
full screen logo would remain on the screen, and you'd have no
further evidence of the problem. I *hate* when BIOS designers
do this. The default should be to disable it.

Without a motherboard model number, it is pretty hard to offer
any other comments.

A PCI Port 80 POST card, can be used to display two digit
"progress" codes. The problem with the concept, is that
the "progress" codes really don't tell you too much. They
aren't that useful for debugging. It would represent one
additional potential source of information about the nature
of the problem, but I can't remember the last time that such
a POST debugging card, helped a user identify a problem with
a system. Such a card is mainly useful for determining whether
a system is completely dead or not, and in your case, we know
a good deal of your hardware is working.

(Scroll to the bottom of this page, to see the two digit hex codes
and the routine they're associated with. The code is written to
port 80 of PCI slot #1, just before the routine is executed.
So seeing a code remaining stable on the LED display, is supposed
to indicate you're "stuck" in that routine.)

(A port 80 card, with ISA and PCI connectors, suitable for ISA
based and PCI bus based motherboards. Cards cost anywhere from
$10 to $100, depending on whether they're coming from Hong Kong,
or from your local computer store.)

In the interim, if you want an approach to use, try simplifying
the system. Disconnect the hard drive and CDROM drive data cables from
the system. Try inserting a MSDOS boot floppy, and see if it
boots from that. Knowing what your boot sequence is at present,
would help determine whether this would do anything or not.
I usually leave mine set to "floppy, CDROM, hard drive", so that
if the CDROM and hard drive fail, the floppy is the very first
thing checked for boot media.

If you have more than one stick of RAM, try each stick by itself,
one at a time. Remember to turn off the power before adding or
removing RAM. I unplug the computer, to remind myself I've really
turned off the power. Use an antistatic wrist strap, clamped to the
chassis, to reduce the chances of ESD damage to the RAM. Store
unused RAM in an antistatic bag.

I would not use the "CMOS clear" jumper, until you've exhausted
all other possibilities. In some cases, a key setting a user
needs, gets returned to a non-useful default value, which is
why using the CMOS clear may be detrimental to making progress.
For example, if a user has busted onboard integrated graphics,
and is relying on a plug-in video card to make their system work,
clearing the CMOS may no longer be practical. So before doing it,
check the downloadable PDF user manual, in the BIOS section, and
make sure you're not completely making it impossible to run the

If your system was completely working, and you wanted to clear
CMOS, then entering the BIOS setup screens and putting things
right, might not be a big deal. But if your system is busted
in some way, clearing the CMOS may only make things worse. It
really depends on whether the default values the manufacturer
has chosen, are useful or not.

Since you're seeing the full screen logo on the screen, I don't
see any point in attempting what I call "beep tests". Since you've
got the full screen logo, much of your system is working. It could
be it is getting stuck due to some PCI card you added that is
broken, a PCI card that is not fully seated in a socket,
an AGP card in a similar situation, a hard drive which has failed
and is "dragging down" an IDE cable. Something along those lines.
If the BIOS flash chip has failed, and the motherboard can't write
the DMI or ESCD, that might be another reason for the situation
you're in. Just to name some possibilities.


Site Timeline