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From: Paul 
Newsgroups: microsoft.public.windowsxp.general
Subject: Re: Dell 780 Problem:
Date: Wed, 15 Nov 2017 18:14:41 -0500
Organization: A noiseless patient Spider
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Mark Twain wrote:
> As I said, the beeps are hard to 
> follow but If I read the beeps 
> correctly I have a master DMA 
> register failure.
> 
> That along with the 1 diagnostic 
> light lit indicating no memory 
> modules detected. 
> 
> Robert

Careful.

You should not remove a DIMM with the power on.
Even if the fans aren't running, the power supply
+5VSB is still delivered by the supply.

You should unplug the computer before working
on DIMMs. That's the only way to be absolutely sure
power is removed. On Asus motherboards, a green LED
stops glowing, indicating it's safe to work. On motherboards
without the green LED, wait at least 30 seconds from
unplugging the power supply, until you work on the DIMM.

To remove a DIMM, you rotate out the latches
to 45 degrees, and that helps ease the DIMM up out
of the socket a bit. Once the contacts aren't gripping
the DIMM, it should then be able to be pulled straight out.

When inserting the DIMM, the center notch has to
align with the "key" in the slot. This prevents
180 degree reversal of DIMMs by accident. Visually verify
when re-inserting, you're putting it in the right way.
(I have to include these instructions, for the sake of
completeness.)

When inserting the DIMM, the latches go to the
45 degree position. The DIMM is then aligned with
the "square" opening in the DIMM slot. The end-guides
guide the ends of the DIMM for its downward trip.

When you push down on the DIMM (to force the fingers
between the contacts), it will cause the
latches to rotate into the upright position again.
You should hear a "click" when the DIMM is in
place, from each end. The latch should be
in the upright position, the protrusion on
the latch should insert into the area reserved for
it on the side of the DIMM.

On DIMM slots which use one latch, and the latch
nearest the video card is a dud, only one end will
be heard to "click". I have a mixture of motherboards
here - most have two latches, but at least one I own,
has a single latch on each DIMM slot.

With a flashlight, look at the fingers on the DIMM.
The "gold" should mostly be hidden below the socket
body, so you can't really see any gold. If you see
a lot of gold glinting back at you, it isn't seated.

DIMMs which are finished "flat" on the end, have
high insertion force. It hurts your fingers to
drive those into the socket. Some of the older memory
standards, the insertion force wasn't nearly as high.
I have some Kingston DDR2 here, it just about
kills me inserting those.

You can blow a DIMM or processor interface, if
the DIMM falls out with the power on, and something
gets shorted together. The most likely way this would
happen, is if one end of the DIMM comes loose, while
the other end stays in the socket. That should
only happen, if the PC is dropped out of a second
story window :-) Kneeing the PC should not do that.

I wouldn't panic just yet, until thoroughly verifying
the DIMM(s) are seated. Remember to unplug the computer.
If there was micro-latchup, removal of power gives
CMOS circuits a chance to recover. Verify with your
flashlight, that each DIMM is fully homed into the socket,
and no gold is showing.

    Paul
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