DDR Questions

Saint wrote:

 > I have a dell that has Dual Channel DDR PC3200 in it. Total of 256MB
 > (2x128MB). I want to put another 512MB in it.
 >
 > I understand that it has to be installed in pairs to keep the memory working
 > in dual channel.
 >
 > Does installing in pairs mean that I not only have to install two DIMMs but
 > I also have no choice but to install only 128MB DIMMs since that is what the
 > machine came with? In other words, do both pairs have to match as well? Or
 > can I keep the pairs of 128MB and then install pairs of 256MB to bring the
 > total memory to 768MB and still have dual channel working?
 >
 > Thanks in advance.
 >
 > Chris

.


You can add a matching pair of 256MB DIMMs, and it will still work in
dual-channel mode. But, you will lose dynamic addressing. All installed DIMMs
must match, to use dynamic addressing mode.
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"Saint" wrote in message

 > I have a dell that has Dual Channel DDR PC3200 in it. Total of 256MB
 > (2x128MB). I want to put another 512MB in it.
 >
 > I understand that it has to be installed in pairs to keep the memory
working
 > in dual channel.
 >
 > Does installing in pairs mean that I not only have to install two DIMMs
but
 > I also have no choice but to install only 128MB DIMMs since that is what
the
 > machine came with? In other words, do both pairs have to match as well?
Or
 > can I keep the pairs of 128MB and then install pairs of 256MB to bring the
 > total memory to 768MB and still have dual channel working?
 >
 > Thanks in advance.
 >
 > Chris

With Dual Channel, you do need to install in pairs, but they can be of mixed
sizes (the pairs, not the DIMMs which constitute a pair).

So, you can go out and buy two of the same 256MB DIMMs and install those
into the 3rd & 4th slot (PC reads it as slot 2 & 3, since it starts at 0).
And then you'd have 768MB.

I cant recall of any motherboards which only have 2 DIMM slots, but anytime
you get a prebuilt, it is a possibility. If you haven't already had a look
inside yet, check to make sure you do have the 4 DIMM slots (although
perhaps this is how you know you have 2x128...)
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In article ,

 > Saint wrote:
 >
  >> I have a dell that has Dual Channel DDR PC3200 in it. Total of 256MB
  >> (2x128MB). I want to put another 512MB in it.
  >>
  >> I understand that it has to be installed in pairs to keep the memory working
  >> in dual channel.
  >>
  >> Does installing in pairs mean that I not only have to install two DIMMs but
  >> I also have no choice but to install only 128MB DIMMs since that is what the
  >> machine came with? In other words, do both pairs have to match as well? Or
  >> can I keep the pairs of 128MB and then install pairs of 256MB to bring the
  >> total memory to 768MB and still have dual channel working?
  >>
  >> Thanks in advance.
  >>
 > You can add a matching pair of 256MB DIMMs, and it will still work in
 > dual-channel mode. But, you will lose dynamic addressing. All installed DIMMs
 > must match, to use dynamic addressing mode.
 >
What's "dynamic addressing mode?"

It's amazing sometimes the disconnect between what's in the chips and
what shows at the motherboard level. I'd been in the standalone DRAM
design business for about 15 years, and decided that I should really
examine the BIOS settings, because knowing the DRAM side I should be
able to figure out how to extract maximum performance out of them. At
that point I also had the chance to have some DRAMs that though I
hadn't designed, some friends had, and I knew their peculiarities and
where they could be pushed (overclocked) a bit. I looked at the BIOS
settings, and most of the names made no sense at all to me. For the
most part, they used a completely foreign nomenclature.

I've never worked on a DDR chip, though I've done SDR. So what is
"dynamic addressing mode?"

Dale Pontius
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Dale Pontius wrote:



  >> You can add a matching pair of 256MB DIMMs, and it will still work in
  >> dual-channel mode. But, you will lose dynamic addressing. All installed DIMMs
  >> must match, to use dynamic addressing mode.
  >>
 > What's "dynamic addressing mode?"

<a rel="nofollow" style='text-decoration: none;' href="http://www.intel.com/design/chipsets/applnots/25273001.pdf" target="_blank">http://www.intel.com/design/chipsets/applnots/25273001.pdf</a>



 > It's amazing sometimes the disconnect between what's in the chips and
 > what shows at the motherboard level. I'd been in the standalone DRAM
 > design business for about 15 years, and decided that I should really
 > examine the BIOS settings, because knowing the DRAM side I should be
 > able to figure out how to extract maximum performance out of them. At
 > that point I also had the chance to have some DRAMs that though I
 > hadn't designed, some friends had, and I knew their peculiarities and
 > where they could be pushed (overclocked) a bit. I looked at the BIOS
 > settings, and most of the names made no sense at all to me. For the
 > most part, they used a completely foreign nomenclature.

Some of the nomenclature does not make sense to me either.

It's more fun when you have different manufacturers using
different nomeclature for the same things.






--
davewang202(at)yahoo(dot)com
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