L.S. said:
If I could ask a follow-up question.
I have an older system, nvidia geforce2 board, amd sempron 3300 @ 1.8mhz and
one 512m stick on memory, ddr333 64x64.
I have an extra stick 1gb, pc3200 ddr @ 400mhz.
Can I run both or not and will the pc3200 run ok in the system?
thanks for any help/advise,
Do you mean "Nforce2 chipset" perhaps ?
It sounds like you're running the Sempron at 11 x 166 ? I think the
multiplier is 11, and the bus is supposed to be 200MHz input clock.
Most of the Nforce2 boards are dual channel. There is one
which has the distinction of being single channel, but as
near as I can tell, that is a logical rather than a physical
implementation (there are two buses, but they function as one).
Most Nforce2 have two data buses, and three address busses. There are
three memory slots. Each memory slot gets its own address bus, which
reduces loading effects when all slots are occupied. Address bus is
a limiting factor in memory bus design (tends to crap out, before
the data bus does).
One data bus has two sticks (the slots are close together). The
third stick is on the second data bus (it has a larger separation
from the other slots).
First, we'll take a "usual" example. A person buys a pair of
matched DIMMs. This would be dual channel. It is dual channel
through the entire address space.
----- 512MB
----- 512MB
-----
With Nforce2, all that matters is that the total memory in each
channel is the same. That gives dual channel performance through the
entire address space. In the above example diagram, I could use
an 8 chip 512MB stick for one slot, and a 16 chip 512MB stick
for the other slot, and it would still be dual channel (unlike
some other dual channel designs).
Now, with your case. Here, one channel has 1024MB total, and the other
has 512MB total. The memory operates dual channel, for the first 512MB
of each channel. So that is 512MB+512MB of dual channel space, plus
the left over 512MB at the top of the memory map, running single channel.
This is "composite" operating mode. I actually modified a copy of
memtest86+ source code, to verify the composite behavior. On my
Nforce2 board, I got about 1400MB/sec for the lower 2/3rds of the memory
and about 900MB/sec for the upper 1/3rd. I used memtest86+ to probe
blocks of memory and measure the bandwidth.
----- 1024MB
----- 512MB
-----
To make the channels match, you could do one of these two
configurations. Here, the total RAM in each channel matches.
----- 1024MB ----- 1024MB
----- 512MB ----- 1024MB
----- 512MB -----
The Nforce2 chipset can use a 1GB (1024MB) stick, but it must
be low density. That means you should not buy the stick of
DDR memory from Ebay, as there is a lot of 1GB high density
RAM for sale on there. This is the definition
(16) 64Mx8 (dual rank, low density, Crucial, Kingston, Newegg sources OK etc)
(16) 128Mx4 (single rank, high density, no-name modules from Ebay, the memory
chip brand is immaterial to the issue)
Note that the "128Mx64" you see in a lot of adverts on the
Internet, tells you nothing about the composition of each
memory chip. So if you say "but my module is 128Mx64", it
could either be high or low density, and still have those
overall dimensions.
Nforce2 will "half-detect" high density 1GB modules. Many of the
Ebay pages selling that RAM, will mention the "high density" label
as a warning. I cannot think of a good reason to buy it. I did
research the modules, and they are "JEDEC approved", but that
doesn't mean the memory is universally applicable and works well.
It is a product which should be avoided, especially if you're going
to resell it later.
If your stick is (16) 64Mx8, then it will be properly detected as
1GB. I had 2x1GB in my Nforce2 before I retired it. (Some people
have experienced issues with more than 2GB installed, so if you
try a total of 2.5GB for example, it might not work. That is
some kind of memory map problem, but I'm not at all sure
how common that is across all motherboard brands. I've read
accounts of people who used more memory, but I don't know
how they did it.)
With regard to speed, I would expect no problems at DDR333 setting.
But running at DDR400 can mean trouble. All you can do, is
test it, and see what happens. I've run DDR400 with a couple
kits of RAM, but it was CAS2 stuff. I've even run 3x512MB
at 2-2-2-6 DDR400, just like the early Anandtech articles
on Nforce2, so it can work. But Nforce2 is *picky* about
RAM, so always test the memory before attempting to
boot WinXP. Memtest86+ from memtest.org is one program
you can use.
HTH,
Paul
Really unstable...