On 12/19/2010 1:07 PM, Bob Villa wrote:
On Dec 19, 10:50 am, Ben wrote:
On 12/17/2010 7:07 PM, mm wrote:



On Wed, 15 Dec 2010 22:17:24 -0500, Ben
wrote:

On 12/15/2010 9:52 PM, mm wrote:
Memory: Does it matter if big DDRs are firsr or second?

Posted to alt.comp.hardware and alt.sys.pc-clone.dell, since the
computer is a Dell and I started the topic in that group, but have
broader questions now.

I have two 512M and two 1G DDR[1]s and they are the same speed PC2700,
the same 333, the same CL 2.5, the same non-ECC and assume everything
else the same except the brand and size.

Does it make a difference if the big pair goes in the first pair of
slots, or if the small pair does???

Is this true for DDR2 and DDR3 also?

Just to be perfectly clear, if you are talking about Dell Precision 360,
Dimension 4600, Optiplex GX270, or Dimension 8300,

It was meant as a general question.

I'm 99% sure I've read that *faster* memory should go in the first
pair of slots, and that makes sense so that one should use the faster
memory most of the time.

But here the speed is the same, only the *size* is different, so does
it matter which one is first?

two memory slots have
black DIMM clips and two have white clips. A matched pair has to go in
a pair of DIMM slots with the same color of clips.

Yes, thanks, the computer I'm working on now is a Dell 4600 and the
manual made that clear.

As a rule, I install
the larger capacity memory in the "first" pair of slots.

But is that a personal practice, or maybe a habit left over from fast
vs. slow memory, or is it really based on some benchmark testing or
recommended by engineers or so forth?

Which is the
"first" pair of slots? Usually the one nearest to the CPU and its mate
with the same color of clips. But when in doubt, read the owner's
manual. Same for DDR2 and DDR3.

These boards all have Intel 865 or 875 chipsets, which dictate the
memory configuration rules.

Way back when I worked in mainframe software development, we and tech
support used to write "RTFB" responses, telling customers the answers to
their questions or solutions to their problems and telling them to read
the ^^&&*(_* book, where the answer could be found... Ben Myers

The Dell owners manual didn't go into such detail.

Thanks again.

There is no difference whatsoever placing faster memory in the first
DIMM slots or the second ones. "Faster" memory is rated to run at a
faster speed than slower memory, but it can and does also run at slower
speeds.

The speed at which memory operates is dictated by the motherboard and
CPU, not by the memory itself which is a passive component. For
example, if you put PC3200 memory in a system with a CPU operating with
a 533MHz front side bus (e.g. the hot-running 3.06 GHz P4), the memory
operates at the lower PC2100 speed... Ben Myers

Ben, wouldn't that lower speed instance be PC2700?

Not in the example I used. PC2100 runs at 266MHz speed, exactly half of
533MHz. Because the memory is double data rate (DDR) each clock
supplies two fetches of data, one from each of the dual channels,
assuming that the memory is installed to allow dual channel operation.

But if you install PC2700 in a system with a CPU running with 800MHz
front side bus, the 865 or 875 chipset mediates the difference between
the PC2700 speed and the FSB. So the slower memory runs OK with the
faster CPU... Ben Myers