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March 13, 2010, 2:25 am
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I have not added RAM to any machine before. Went through the
machine specifications are as follows:Operating System Microsoft Windows XP
Professional Service Pack 3 CPU Type Intel Pentium 4 640, 3200 MHz (16 x
200) Motherboard Name Hewlett-Packard HP Compaq dc7600 Convertible Minitower
Motherboard Chipset Intel Lakeport-G i945G BIOS Type Compaq (05/18/05) I
have already backed up the machines data in case anything goes wrong.Anything in
particular I need to be careful/aware of?Any suggestions would be appreciated.
Re: installing DDR2 RAM chips in a HP xw4600 workstation
I'm not sure what kind of information you're looking for.
And that makes this post longer than it has to be.
The motherboard has four slots. You haven't indicated how
much memory is currently in the computer.
The 945G chipset is technically capable of holding 2GB
capacity DIMMs. But if you do that, you can only cost
effectively populate two slots with the 2GB DIMMs, leaving
the remaining slots blank. I've put some examples of
To start, say the computer shipped with 2x512MB. They'd be in
a pair of same-colored slots. You could add a package of memory
with 2x1GB sticks in it, filling the remaining slots. Why is
this useful ? Because the amount of address space available to
address main memory, is limited. Using 3GB total memory results
in none of the extra memory being wasted.
512MB \___ Channel A
512MB \___ Channel B
If the machine shipped with 2x1GB installed, then you could either
buy 2x512MB or 2x1GB. I'll make an example out of the latter configuration,
to be a bit different. The total memory is 4GB. When you boot Windows,
it may say "3.2GB free". Notice that 800MB has gone missing. That might
happen, if there is a separate video card plugged in as an upgrade.
The less address space used for video, the better use you'll get from
the memory upgrade.
1GB old \___ Channel A
1GB new /
1GB old \___ Channel B
1GB new /
As far as I know, this is a legal configuration, but is not practical
in terms of an incremental upgrade strategy. This too would report
"3.2GB free". The actual number varies, depending on the video card.
I have a machine here, that reports "3.5GB free", because it had
a PCI video card.
2GB new \___ Channel A
--- --- /
2GB new \___ Channel B
--- --- /
When installing memory, turn off power to the computer. I like to
unplug the computer, as a means of assuring that all power has
For anti-static protection, the algorithm is "charge equalization".
The word "grounding" isn't really what the hardware needs. What you
want, is for all components to be at the same electrical protection.
We've ingrained the notion of "grounding" into people, because, in
a sense, it does lead to all components being at the same potential.
But that doesn't tell the whole story.
If you look at the materials used to hold the memory, you'll notice
they're plastic. Plastic normally holds a static charge quite nicely.
This plastic has mixed with it, something which makes the plastic
slightly conductive. If you "zap" the plastic package with your
finger tip, the high resistance of the plastic allows the charge to
redistribute slowly. A slow distribution of charge means a low
peak current flow, which is less damaging. The conductive plastic
helps protect the memory while it is shipped and handled.
So two mechanisms are at work, when it comes to antistatic precautions.
1) Slow equalization of charge, so that all devices are at the
same electrostatic potential.
2) Bringing all the electrical parts to the same potential, before
plugging them together. That means there are no "arcs or sparks"
when they're installed.
This is an example of a hardware aid, to help bring some things to
the same electrostatic potential. This is a wrist strap.
You clip the alligator clip on the end, to some shiny metal on the
chassis. I like to use a screw on an I/O connector on the back of
the computer, as the clip should hold there nicely.
When your wrist is in the strap, the cord of the strap is actually
a high resistance path. There could be a 1 megohm resistor or higher,
in series in the strap. That strap is *not* just a straight piece of
wire, and substituting a wire is not quite the same thing. If you
want to make a wrist strap out of some wire, remember to buy and
place a high resistance 1/4W resistor in series with it. Resistors
are available up to 22 megohms, at retail.
If you were holding the tray with the memory DIMMs in your hand,
while the strap is connected to the chassis, within a few seconds,
all items are at the same electrical potential. Now, you can plug
in the DIMMs. Don't handle the gold contacts, as it leaves salt
stains on the contacts. The objective is to leave the contacts
clean. So little gold is used in the gold plating, that the
less precious metals underneath, are still exposed to the elements.
Keeping your finger prints off the contacts, means less long
You don't have to buy the wrist strap. You can "emulate" the process
of charge equalization, without a strap. It would mean holding
onto the chassis with one hand, the memory tray with the other,
to bring them to the same potential, then remaining in contact
with the chassis, until the memory is installed. And, doing it
in such a way, that equalization is through a high resistance
path. The tray or bag the memory comes in, is a high resistance
path. Your body is not. Your body is a low resistance path
(~100K ohms). You can handle the DIMM, once it is equalized, but
you need to keep you, the chassis, and the DIMM at the same
potential, until the DIMM is installed.
Using the wrist strap gives you more physical freedom
during the installation. It takes a fair bit of dexterity
to emulate the wrist strap, without dropping the DIMM etc.
If you're a butter fingers, having your very own strap
is a good investment.
Memory has a few standard mechanical features. The latches on the
DIMM slot, are cam ejectors for helping the DIMM out of the socket
later. There is an indentation on the side of the DIMM, and when the
latch is fully upright, a feature of the latch should align with
the indentation on the side of the DIMM. That helps prove to you,
that the DIMM is fully seated. You shouldn't be able to see any
gold showing, if the DIMM is really down into the socket. And where
the key meets the slot, the key should be just about touching
the slot. You should be able to verify visually, that the thing
is seated, as well as getting a satisfying "click and krunch"
when pushing down on the DIMM.
The memory comes in various heights. I have some low-profile
memory I got from Kingston here. I've found that it takes
a little extra pressure to install that stuff in the DIMM slot.
So much pressure, that it hurts your fingers. Just in case
you were wondering whether you should be "feeling any pain"
or not :-) Regular height memory seems to fit in with a
little less pressure, and you won't feel any pain when
installing that stuff.
Align the slot in the contact area of the DIMM, with the
key in the DIMM slot itself. The DIMM will not seat, if
you flipped it 180 degrees and tried to install it backwards.
The key is there to ensure you're installing the right
family of memory (DDR, DDR2, DDR3), as well as guide you
to putting it in the right direction. Don't push down on
the DIMM, if you've aligned it the wrong way.
Your computer is a pre-built, so the motherboard should be
well supported underneath. Some people who build their
own computers, don't have any standoffs under the motherboard,
near the RAM slots. This results in the motherboard bending
in an excessive manner when memory is installed. It is
OK for the motherboard to bend a little bit, but there
should be some mechanical support underneath that
area of the motherboard, as too much bending can break
a solder joint.
OK, now your memory is in place, all latches are upright,
and none of the DIMMs are tilted on an angle (tilted
because only one end is seated).
Now, plug in the power, switch it back on via the switch
on the back of the computer, and prepare for *testing* .
Download memtest86+ from memtest.org and prepare a floppy,
a CD ROM or a USB flash stick. Run memtest86+ for a couple
complete passes. If no memory errors are detected, you can
boot into Windows. If memory errors are detected, you have
to resolve the issue, before booting back into Windows.
Don't boot into Windows if the memory is not working right.
If you need more help with that, simply remove the new
memory, and return the machine to the original state.
You should run memtest86+, even on the original memory,
to see if it has any problems. Then, post back for more
In this picture, you can see the current Pass is at 41%,
and the Pass counter is still at "0". You want the Pass counter
to hit 2, with no errors showing, as proof you're in good
shape. When you've completed testing, press <esc>, and
remove the memtest86+ boot media. Memtest86+ is a self-booting
test program, and uses no operating system. So Windows is
not running, when you see this screen.
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