On Thu, 04 Jun 2009 14:41:36 -0500, Ken wrote:

Sjouke Burry wrote:
Ken wrote:
I was adding some memory (DDR) to a Compaq 6000T computer to send
to a friend. This computer is a Celeron 2 GHZ that can accept up to 2
Gig of RAM. The minimum speed is PC2100 and the MB has two slots for
memory. It had been running with 512 MB (2x256) and can accept either
high density or low density RAM in any combination up to 2 GB.

Now the interesting part: I purchased two sticks of low density
PC3200 DDR so that I could put the maximum memory in the computer
before sending it out. Upon receiving the RAM I removed the existing
RAM and installed both sticks of PC3200 RAM WITHOUT having removed the
A/C power cord. Next I ran a memory test on the new memory to make
sure no errors occurred. It passed without error and recognized the
full 2 GB. Thinking everything was fine, I unplugged the computer from
the A/C and worked on something else.

Upon returning to the computer I plugged in the power cord to the
A/C and immediately the computer tried to start without having pushed
the power start button on the computer front. It did NOT successfully
start, but went into an oscillation of the power supply starting and
stopping every half second or so. (Pushing the power button during
this event had no effect at all.) During this oscillation the power
on LED would flash and the power supply fan would start and stop. I
unplugged the power cord after a few seconds of this and waited a
couple of seconds before plugging it in again. Upon plugging in the
cord again, the same thing happened again. It went into a cycle of
turning on and off the power.

Wondering what could possibly have gone wrong, I returned the old
RAM to the slots in place of the new RAM and plugged in the power
cord. It behaved normally, whereas the pushing the power button
started the computer. Thinking the larger size RAM might be drawing
more current and making the power supply suspect, I installed a 300W
PS in place of the 250W that had been in the computer. This had no
effect, so I returned the 250W one to the computer. The 250W power
supply had an LED on the back of the PS indicating (I suppose) that
the standby power was up.

What I discovered was that if I waited to plug in the power cord
again until after the LED went out, the oscillation I described above
would NOT occur, even if both sticks were 1 GB PC3200 ones! It was as
if the standby voltage was not coming up fast enough when the PS had
totally discharged, but if you returned the A/C when the LED had just
gone out all was fine regardless of the RAM.

Since I did not want to give someone a computer that could go into
a power oscillation like I describe above, I wired in a reset button
as this computer did not come with one. After establishing that the
reset button did work properly, I wanted to see if pushing the reset
button could stop the oscillation if pushed. It did not! So it
seemed if the 2 GB of PC3200 RAM was installed, and power was to be
restored after something like a power failure, the oscillation would
occur. I could not live with this possibility.

Since I wanted to install as much memory as possible in the
computer, I experimented to see if something less than the 2 GB of RAM
would have the same problem. It seems that as long as both sticks
were not the 1 GB sticks, everything worked fine. I ended up
installing one 1 GB stick of PC3200 and one 512 MB (high density)
stick of PC2700. From that point on, it never failed as described
above. So my question is this: Why did the computer fail to behave
properly ONLY when power was completely removed and ONLY when two 1 GB
sticks of PC3200 were installed???? Since it is no longer a problem,
I am curious to understand what might have been happening. Any
theories???


I would suspect wrong bios settings.
remove the battery for 15 minutes,or find the bios reset strap,
and let the bios initializee itself to factory settings.
Dont forget to put the reset strap back in its old position.

I appreciate your suggestion, but the computer power never really was
applied in the failure I described. Hence the bios settings could not
have come into play since there was no power to read them. Also,
without having changed any of them, they worked for a boot when the
power cord had not been removed with any combination of RAM.

Now I could be missing something.

I think you are, the bios is mis-configured perhaps, and resettng it
to factory would perhaps correct the problem.

If so, I am open to what I am
overlooking. My theory has to do with the standby voltage not coming up
soon enough to reset the logic properly, but I do not understand why the
size of the RAM has anything to do with it.

Maybe it doesn't?