Question about memory

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I had a Dell Dimension 2400 Cleron that just recently died.  Not having
gobs of money available I purchased a barebones system for $159 with a 400W
power supply and an ASRock LG 775 Dual-VSTA (not a spelling error - not
Vista) SATA 2 board.  The mobo is the ultimate upgraders dream.  It accepts
all my old parts and has slots for new things.  The processor that came
with the case and mobo is a Celeron D 356 @ 3,33 Ghz and seems very crisp
using my old DDR memory - though the board will accept DDR2 memory.

My question is about Dual Channel versus single and about DDR2 vs. DDR.
I have mixed memory at the moment.  A PC2700 256mb Micron and a 512mb
PC3200 Kingston.  The manual that came with the mobo says to enable dual-
channel you must have the same type of chip in each slot.  So if I bought a
512mb Kingston chip giving me a Gig of memory would I have better
performance than if I bought simply a 1gb chip at 667 Mhz DDR2?

The prices are roughly comparable between the older Kingston at 512mb and
new 1gb chip.  And the option of keeping the old Kingston is not available
as one cannot mix DDR and DDR2 - but I could buy a 1gb DDR at about the
same price as a DDR2.

soliciting thoughts?


Re: Question about memory

newton wrote:
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2x512MB PC3200 in dual channel mode equals 6.4GB/sec theoretical.

1x1GB DDR2-667 would be 667*8 = 5.336GB/sec (i.e. PC2-5300) so less than the

Using two DDR2-667 sticks would give 667*8 * 2 = 10.6GB/sec

So if you're on a limited budget, then a 512MB DDR for $27 or so,
will give you a pair of PC3200 512MB DIMMs.

Sometimes the impact of dual channel is not that great. One place
I noticed it made a difference, was on a motherboard with integrated
(chipset) graphics, where the desktop seemed a bit snappier after
getting dual channel mode working. If you have a separate graphics
card, then the video card memory is used for the frame buffer, so the
same effect won't exist.

The change might be more or less transparent to you. If someone
blindfolded you, and put either one or two sticks in the machine,
and then you tried to do email or web surfing, you might not be
able to tell whether one or two sticks was in use. Of course,
if the computer is starved for memory, the paging to disk would
tell you. But if there was sufficient memory that just the memory
was used with no paging, you might not be able to tell.

A benchmark can tell, because benchmarks are more dependent on system
resources. As would a stopwatch test, like if you were doing DVDShrink
and waiting for the results. But for a lot of interactive activities,
the effect would be less noticeable.

A couple days ago, I saw a 2x1GB DDR2-800 CAS5 kit for $75, so you can do
a pretty amazing memory upgrade for pretty cheap.


Re: Question about memory

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thanks for the info - still confused somewhat.  The old adage was that
more memory is always better than less.  What I failed to make clear I
think is that I could obtain a DDR 1GB stick at about same money as a
DDR2 stick.  Now wanting to throw things away - I would have 1.5 GB of
DDR memory - if I just purchased the 1GB DDR2 - would it be better to go
that route or just maintain.

And the 800lb gorilla in the room is that DDR will not be supported by
new motherboards.  This mobo does but it is due to be discontinued.  So
maybe take a bite and buy a single 1GB DDR2 that can be used later.



Re: Question about memory

Edward W. Thompson wrote:

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On a mixed memory type machine, you can only use one type of memory
at a time.

If you have one stick of DDR, then you'd get a second stick to go with

Or, if you want to use DDR2, you unplug the existing DDR, and use the
DDR2 instead.

If the machine type is mixed memory, and there are four slots, then at
most only two slots can be filled at a time. Either two DDR will be
present maximum, or two DDR2 will be present maximum. At least two
slots will always be blank.

What I'm not sure about, is if you put 512MB DDR + 1GB DDR, whether
the chipset will run with that. Years ago, some chipsets were "pure"
dual channel. Which means you had to match the memory on the two
sides, for it to work. Intel at the time, was the first I'm aware of,
to allow using all different sizes of memory at the same time. They
called that virtual single channel mode. Eventually, the Athlon64 did
the same thing. I would hope that VIA and SIS chipset do that now as well,
and if I'm lucky, I can find a good motherboard manual that gives a table
of all useful configurations. But in this case, I didn't get lucky, and
the manuals I looked at weren't any help. I expect you're OK, no matter
what you want to do, but I cannot prove it with documents for your chipset.

It looks like $25 is enough to buy you 512MB DDR, and $60 would buy
you 2x1GB DDR2 of some speed. If you wanted real fancy memory, with
special heat spreaders, low CAS, really high clock speed, you can spend
many times that much.

You can use the customer reviews on Newegg, to find examples of good


Re: Question about memory

newton wrote:
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OK, you're confused, but consider this.

512MB + 512MB  = works in dual channel mode
                  bandwidth 6.4GB/sec
                  total memory 1GB

1GB + 512MB    = works in virtual single channel mode ???
                  (I just spent 30 minutes trying to verify this and
                  cannot find any proof it runs virtual single channel.)
                  bandwidth 3.2GB/sec (one stick at a time only)
                  total memory 1.5GB

If you routinely keep more than 1GB of memory full while using
the machine, then yes, the 1.5GB configuration could be better,
if it helped avoid paging of memory out to disk.

But for most desktop usages, you don't fill the memory that often.
On my total 1GB memory machine, I use a little over 600MB when
playing BF2, and for a lot of other stuff, I don't come close to

I've only gone heavily into swap, just once in the last year or
two, and that was printing the world's largest web page. My disk
was grinding like crazy for that.

If I had Photoshop for the machine, then I'd probably upgrade to
2x1GB, to make more room for undo buffers and large images. The
rule there, used to be, a minimum of 5x the size of the image.
So 2GB would allow handling at least a 300MB image (leaving room
for the OS etc.)

I saw a 1GB DDR2 stick (Kingston) for $30 tonight, and two of those
would be $60. That is pretty damn cheap.

Another thing I should point out, is certain memory types and sizes
have issues. For example, Ebay is awash in 1GB DDR memory made using
128Mx4 chips. The adverts usually list "compatible chipsets", which is
a way of saying the memory is crap. You may save $20 by buying one of
those, but I guarantee you'll regret your purchase in the long run.
It'll be the day you try to move it to another motherboard. Or sell
it to someone else, and they have problems with it.

This page shows the cheap stuff on the right, and the other two are
the good stuff (64Mx8 chips). I don't think the price differences
are quite as large today, and this advert is pretty old.

So if you are really strapped for cash, buy one 512MB to match what
you've got.

The next time you have $60 to $75 or so, you'll be able to buy
2x1GB DDR2 as a replacement. You won't see a big difference (because
the memory is not going to be filled that often), but if there is
some game that really chews up RAM, then you'll be all set. Or
if you have a copy of Photoshop, the difference could help.
For a lot of other uses, a total of 1GB is enough.

I've used a machine with 512MB of RAM and WinXP, and it was a little
bit cramped. But the 1GB total I have on the Win2K machine I'm typing
this on, hasn't bothered me at all.


Re: Question about memory

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My understandis that DDR amd DDR2 memory are not interchageable as
they have different physical configuration.  Is this not correct?

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